THE death toll from a suicide attack on Istanbul's Ataturk Airport has risen to 41 as Turkish officials blamed Islamic State militants.

Twenty-three Turkish citizens and 13 foreign nationals were among those killed, and almost 150 other people were injured, when three suicide bombers targeted the airport on Tuesday evening.

Turkish prime minister Binali Yildirim said the bombers arrived at the airport in a taxi and blew themselves up after opening fire on passengers, but there are conflicting accounts of the attack.

A Turkish official said authorities are going through CCTV footage and witness statements to establish a preliminary timeline and details of Tuesday evening's attack, describing the investigation as "a jigsaw puzzle".

The Haber Turk newspaper reported that one attacker blew himself up outside the terminal, then two others opened fire at the point where the X-ray machines are.

It said one attacker was shot at while running amid fleeing passengers, then blew himself up at the exit. The third attacker went up one level to where the international departures terminal is, was shot by police and blew himself up.

Airport surveillance video posted on social media shows the moment of one blast, a huge ball of fire, and passengers fleeing in terror. Another appears to show an attacker, felled by a gunshot from a security officer, blowing himself up seconds later.

It was the latest in a series of attacks in Turkey in recent months which have scared away tourists and damaged the economy, which relies heavily on tourism.

As dawn broke over the destroyed terminal, workers began removing debris left by the blast. The airport has partially reopened but an information board inside showed that about one-third of scheduled flights had been cancelled, with a host of others delayed.

Speaking at the airport, Mr Yildirim said all initial indications suggest the Islamic State group, also known as Daesh, was behind the attack.

"The findings of our security forces point at the Daesh organisation as the perpetrators of this terror attack," he said.

"Even though the indications suggest Daesh, our investigations are continuing."

Turkey shares long, porous borders with Syria and Iraq, war-torn countries where IS controls large pockets of territory. Authorities have blamed IS for several major bombings over the past year, including on the capital Ankara, as well as attacks on tourists in Istanbul.

Turkey has stepped up controls at airports and land borders and deported thousands of foreign fighters, but has struggled to tackle the threat of IS militants while also conducting vast security operations against Kurdish rebels, who have also been blamed for recent deadly attacks.

The devastation at Istanbul's airport follows the March attack on Brussels Airport, where two suicide bombings ripped through check-in counters, killing 16 people. The Islamic State group claimed responsibility for that attack, as well as a subsequent explosion at a Brussels subway station that killed 16 more people.

Belgian prime minister Charles Michel said on Twitter: "Our thoughts are with the victims of the attacks at Istanbul's airport. We condemn these atrocious acts of violence."

Turkish airports have security checks at both the entrance of terminal buildings and then later before entry to departure gates.

Mr Yildirim called for national unity and "global co-operation" in combating terrorism.

"This (attack) has shown once again that terrorism is a global threat," he said. "This is a heinous planned attack that targeted innocent people."

He suggested that the attack was linked to what he said was Turkey's success against Kurdish rebels, as well as steps Ankara took on Monday towards mending strained ties with Israel and Russia.

"It is meaningful that this heinous attack came at a time when we have become successful in the fight against separatist terrorism... and at a time when we started a process of normalising ties with our neighbours," he said.

Eyewitness Adam Keally, from Boston, said he heard gunfire followed by several explosions, then saw people "very badly injured".

Hevin Zini, 12, had just arrived from Dusseldorf, Germany, with her family and was in tears.

"There was blood on the ground," she said. "Everything was blown up to bits... if we had arrived two minutes earlier, it could have been us."

Two South African tourists, Paul and Susie Roos from Cape Town, were at the airport and due to fly home at the time of the explosions.

"We came up from the arrivals to the departures, up the escalator when we heard these shots going off," Mr Roos said. "There was this guy going roaming around, he was dressed in black and he had a handgun."

Prime Minister David Cameron described the terrorist attack as "hideous".

Mr Cameron, in Brussels for what is likely to be his final summit meeting with fellow EU leaders, said the UK would continue to work with the other countries after Brexit on "keeping our countries safe, keeping our people safe - and it's particularly important to say that tonight again when there has been another hideous terrorist attack in Turkey".

BBC correspondent Mark Lowen was on a plane on the runway after landing at the airport and said he was held on the tarmac for around four hours before being allowed off the aircraft and into the terminal.

Reporting from the scene he said: "You can see how chaotic the situation is here. Huge crowds of people are trying to get into the terminal building."

A British man who entered the airport moments after the explosion said it was "like something out of a disaster movie".

Laurence Cameron told Good Morning Britain: "It was just a sea of people, screaming, running towards me. I initially thought it was a hoax or something. It became apparent quite quickly that something was wrong.

"All the passport desks had been abandoned, police were everywhere, guns drawn... it was chaos."

Flights in and out of the airport, which is one of the busiest in the world, were suspended after the attack but it has since reopened.

The Turkish Airlines website says operations have restarted and told passengers to monitor flight information.

Turkey has suffered several deadly attacks in recent months which have been blamed on Kurdish separatists or IS.

Travel guidance on the Foreign Office website for anyone in Turkey or planning a trip there says:

There has been an attack at Ataturk International Airport in Istanbul. If you are in the area follow the advice of the local security forces.

Flights to and from Ataturk International Airport are resuming gradually. Speak to your carrier for updated travel information before travelling to the airport.

The Foreign and Commonwealth Office (FCO) advise against all travel to within 10km of the border with Syria and to the city of Diyarbakir.

The FCO advise against all but essential travel to:

  • The remaining areas of Sirnak, Mardin, Sanliurfa, Gaziantep, Diyarbakir, Kilis and Hatay provinces
  • Siirt, Tunceli and Hakkari

Security force operations against the PKK and related groups are ongoing in the Sur district of Diyarbakir. The FCO advise against all travel to the city of Diyarbakir. Similar operations have taken place in Sirnak and Hakkari. You should take extreme care in these areas. 

Over 2,500,000 British nationals visit Turkey every year. It’s generally safe to travel but you should take additional safety precautions. You should be alert to your surroundings and remain vigilant in crowded places popular with tourists.

Terrorism: The threat from terrorism remains high. Terrorist groups, including Kurdish groups, Daesh (formerly referred to as ISIL) and far left organisations, continue to plan and carry out attacks. Further attacks are likely. Terrorist groups, including Daesh and the Kurdistan Freedom Falcons (TAK), have publicly threatened to attack tourist sites in Turkey. You should take extra care in public places – particularly those visited by foreigners. Be vigilant, follow the advice of local security authorities, monitor media reports and keep up to date with this travel advice.

On 12 January 2016 there was a suicide bomb attack against tourists in Sultanahmet in Istanbul in which 10 people died. On 19 March 2016 a similar attack against tourists on Istiklal St in Istanbul killed 4 people.

On 17 February 2016 a large bomb attack near a military barracks on Eskisehir Road in Ankara killed 28 people. On 13 March 2016, a similar attack killed over 30 people at Kizilay Square in central Ankara.

On 27 April 2016 there was a suspected suicide bomb attack at Bursa Ulu Mosque. The bomber was killed and 7 people slightly injured.

On 1 May 2016 a bomb attack at the Central Police Station in Gaziantep killed two police officers and injured 23 others.

On 7 June 2016 a bomb attack in the Vezneciler area of Istanbul killed 7 police officers and 4 civilians. 36 people were injured.

On 28 June 2016 Ataturk International Airport in Istanbul was attacked. More than 30 people were killed.

Attacks are likely to target the Turkish state, civilians and demonstrations. Nevertheless, it’s increasingly likely that some attacks will also target western interests and tourists from western countries, particularly in the major cities, as was the case in Istanbul on 12 January and 19 March 2016. To date most attacks in Turkey have taken place in the south and east of the country and in Ankara and Istanbul. There is a heightened risk of terrorist attack against the aviation industry in Turkey.

Turkish authorities have successfully disrupted attack planning in the recent past. The Turkish authorities have said that security has been tightened in response to recent attacks. Nevertheless, further attacks are likely, could be indiscriminate and may target or affect places visited by foreigners.