THE string of explosions in London yesterday were the latest in a long and bloody line of outrages against western targets by suspected al Qaida fighters.

At least ten other terrorist attacks have occurred since September 11, 2001, when Osama bin Laden's organisation used operatives willing to die to hijack passenger jets and fly them into the World Trade Centre.

The attacks on New York, the Pentagon, and a hijacked plane that crashed into a field in Pennsylvania, claimed nearly 3,000 lives - including those of 67 Britons - and became the world's largest act of terrorism.

Subsequent attacks included;

* March 11, 2004 - a series of bombs ripped through commuter trains in Madrid, killing 191 people and wounding 1,500.

The Spanish government, a supporter of the war on Iraq, initially blamed the Basque separatist group Eta, but al Qaida later claimed responsibility.

The government's handling of the situation led many people to turn against it in elections three days later when the opposition Socialists, who pledged to pull Spanish troops out of Iraq, were swept to power.

* November 15, 2003 - terrorists said to be linked to al Qaida bombed two synagogues in Istanbul, Turkey.

Five days later, on November 20, two more suicide car bombings in Istanbul hit the British Consulate General and HSBC bank's headquarters in the city.

The series of attacks killed 61 people - including British Consul-General Roger Short - and injured hundreds more.

Analysts said the November 20 bombings showed that al Qaida had realigned its sights towards attacking British targets.

* November 9, 2003 - Saudi authorities claimed al Qaida was behind a suicide car bombing that killed 17 people in Riyadh.

* August 5, 2003 - Jemaah Islamiya - an al Qaida-linked group - was blamed for a car bombing of the US-run JW Marriott luxury hotel in Jakarta, which killed 12 people.

* May 13, 2003 - a series of suicide bombings in the Saudi Arabian capital, Riyadh, killed at least 34 people, in attacks on housing compounds for foreigners.

* December 2002 - a suspected Muslim extremist, cradling his hidden gun like a baby under his jacket, slipped into a Christian hospital in southern Yemen and opened fire, killing three American missionaries and seriously wounding a fourth. Yemeni officials said the gunman was linked to al Qaida.

* November 28, 2002 - a vehicle packed with explosives ploughed into the Paradise Hotel near the port of Mombasa, in Kenya, killing 11 Kenyans and three Israeli tourists.

In a simultaneous attack, two shoulder-launched missiles were fired at an Israeli passenger plane nearby but narrowly missed the aircraft.

* October 12, 2002 - two bombs exploded in a busy nightclub area on the Indonesian island of Bali, killing 202 people, including 28 Britons.

One hit Paddy's Irish Bar in the island's Kuta tourist district and the second exploded in a van outside the Sari nightclub in the same area.

The al Qaida-linked terror group Jemaah Islamiyah was blamed for the attacks.

* June 2002 - a suicide bomber blew up a truck at the US consulate in Karachi, Pakistan, killing 14 Pakistanis.

* December 2001 - an attempted suicide attack on a Paris to Miami airliner by London-born Richard Reid, an al Qaida sympathiser, was thwarted when he was overpowered by passengers as he tried to ignite explosives in his shoe. He was jailed for life by an American court.

No stranger to fears of attack

THE city of London is sadly no stranger to terrorists.

The capital has been the target of numerous attacks throughout the past three decades.

However, while yesterday's bomb blasts are being linked to al Qaida fighters, the explosions the city suffered during the 70s, 80s and early 90s were at the hands of the IRA.

In 1993, a massive truck bomb in Bishopgate ripped through the heart of London, killing one man and injuring more than 40 others.

The explosion shook buildings and shattered hundreds of windows, sending glass showering into the streets below.

A medieval church collapsed and Liverpool Street underground station was wrecked.

The cost of repairing the damage came to more than £350m.

Although police received coded warnings, they came too late and officers were still evacuating the area when the bomb went off.

The explosive was home-made, using about a ton of fertiliser, and was similar to the bomb which devastated the city's Baltic Exchange, killing three people, just a year before.

These attacks sparked the introduction of the "Ring of Steel" - the popular name for the security and surveillance cordon surrounding the city to combat IRA and other terrorist threats.

Roads entering the city have been narrowed and have small chicanes to force drivers to slow down so their cars can be recorded on security cameras.

These roads typically have a paved strip down the middle with a sentry box where policemen can stand guard. Some roads were closed to traffic entirely.

Despite the term "Ring of Steel", the roadblocks and chicanes are actually made with concrete blocks, which are wedged together.

Fears began to subside following the introduction of these measures and the IRA ceasefire in August 1994.

However, the IRA's return to bombing operations reminded the public how well organised it remained.

In 1996, a bomb blast at London's Canary Wharf killed two men. The IRA claimed it chose to break its ceasefire in England rather than Northern Ireland, knowing it would have a greater impact on the Government.

The last attack on London by the IRA came in 2001, when a car bomb exploded just yards outside the BBC's headquarters.

The blast was part of an ongoing campaign of attacks by the Real IRA. The dissident terror group was also responsible for the August 1998 Omagh bombing, which claimed 29 lives.

These attacks added to the call for heightened security worldwide following September 11 and, as a result, the Ring of Steel was widened in March 2003.

The new zone, between Holborn and Victoria Embankment, covers businesses employing 45,000 people.

The measures include automated number plate recognition cameras at entry points - similar to those used in London's congestion charge scheme.

Armed police regularly patrol areas popular with shoppers and tourists and concrete blocks have been placed in front of high-profile buildings to deter car and truck bomb attacks.