On September 11 2001, the world watched on in horror as a co-ordinated terrorist attack sparked a “battle between the free and democratic world and terrorism”.

19 men hijacked four commercial airplanes on the morning of September 11, 2001 and travelled towards major US landmarks in an attack orchestrated by al Qaeda leader Osama bin Laden.

The 9/11 terror attacks against the US claimed the lives of 2,977 victims.

Suspicion following the attacks immediately falls upon Islamist terrorist group al Qaida and its leader Osama bin Laden, who is in Afghanistan under the protection of the Taliban.

When the Taliban refused to hand over bin Laden, the US and its allies prepared to invade.

Tony Blair, UK Prime Minister at the time, did not confirm British forces involvement until October 7 and the first UK troops were not deployed until November.

But Blair spoke to the UK on the day of the attacks and all but confirmed that the UK would be joining the US in the fight against terrorism.

Here is what he said:

Tony Blair’s statement to UK following 9/11 attacks

“The full horror of what has happened in the United States earlier today is now becoming clearer.

“It is hard even to contemplate the utter carnage and terror which has engulfed so many innocent people

“We have offered President Bush and the American people our solidarity, our profound sympathy and our prayers. But it is plain that citizens of many countries around the world, including Britain, will have been caught up in this terror.

“I have just chaired an emergency meeting of the British government's civil contingencies committee and I would like to explain some of the measures that we have agreed to take here.

“There are a range of precautionary measures. We have stepped up security at airports to the highest levels. No flight will take off from the United Kingdom for which we cannot apply the highest standards of security for air crew and passengers. Private flights have been stopped except where specifically authorised. Flightpaths into London have been changed so that there will be no civil overflights over central London.

“Security has been increased over the full range of government buildings and military premises. The police across the whole of the UK are on full alert. All our defence facilities around the world have been moved to high alert to ensure the protection of British service personnel.

“Advice has been given to major financial and business institutions about appropriate security measures. A number of other security measures have been taken and of course we are in close touch with US, European and other allies, and are cooperating with them on issues of security.

“All relevant ministers remain in communication and the committee, the civil contingencies committee, will meet again tomorrow at 8am.

“Obviously, some of these measures, not least the effects upon airports, will lead to some disruption and I hope people will understand that.

“But other than the specific measures we have taken, all that we have advised others to take, business and everyday life can continue as normal.

“As for those that carried out these attacks, there are no adequate words of condemnation. Their barbarism will stand as their shame for all eternity.

“As I said earlier, this mass terrorism is the new evil in our world. The people who perpetrated have no regard whatever for the sanctity and value of human life. And we, the democracies of the world, must come together to defeat it and eradicate it.

“This is not a battle between the United States of America and terrorism, but between the free and democratic world and terrorism. We therefore, here in Britain, stand shoulder to shoulder with our American friends in this hour of tragedy. And we, like them, will not rest until this evil is driven from our world.”