The British Foreign Secretary, Mr Jack Straw, flew to Istanbul in Turkey last night after identifying al-Qaeda as the prime suspect for yesterday's suicide attacks on British interests which left at least 27 dead and hundreds injured. Frank Millar, London Editor, and Nicholas Birch, in Istanbul, report.
The British consul general, Mr Roger Short, was among those killed in the attacks on the British consulate and on the Turkish headquarters of HSBC Bank.
The building housing HSBC also included Marks and Spencers and Tesco, reinforcing the belief in Whitehall that this was an anti-British attack which Mr Straw said bore "every hallmark" of al-Qaeda and its associates.
In London the British Prime Minister, Mr Tony Blair, and US President George Bush condemned the attacks and vowed there would be no let-up in their "war" on terrorism in Iraq and around the world.
The Istanbul blasts occurred around 11 a.m. local time (9 a.m. GMT), one in the centre of the city and the other four miles east in the heart of the financial district. They could be heard more than two miles away, and vast clouds of yellow smoke hung over the city.
The explosions came only six days after suicide bombers partially destroyed two city synagogues, killing 23 people and wounding more than 300.
Saturday's attacks are now known to have been the work of two Turks from the mainly Kurdish town of Bingol, both thought to have trained in Pakistan and fought with the Taliban in Afghanistan.
An hour after yesterday's attacks, a man telephoned Turkey's semi-official Anadolu Ajansi agency to say that the attacks had been "the joint work of al-Qaeda and IBDA/C", an extremist Turkish Islamic group which in the past has limited itself to attacks on individuals.
"Our attacks on the centres of international freemasonry will continue," he is reported to have said.
The call raises suspicions that this could be the work of the same group responsible for Saturday's synagogue bombings.
But a similar claim of responsibility made on Saturday was largely discounted by Turkish terrorism experts, who say that the IBDA/C is too small to carry out such organised attacks.
"There are definite similarities between the two joint attacks," Turkey's Interior Minister, Mr Abdulkadir Aksu, told reporters.
"It seems as though trucks were used to carry explosives."
Fertiliser bombs weighing 400kg were used in Saturday's attacks. It appears as though yesterday's were considerably bigger.
Eyewitnesses at the scene of both attacks reported that this was the work of suicide bombers. In front of the HSBC building, passers-by saw a dark truck stop at the traffic lights before exploding.
As on Saturday, most of the victims were passers-by, or the drivers of other cars.
Warning that media speculation on the attacks could hamper investigation, Mr Aksu also announced that Turkey was banning media coverage at the sites "to investigate the incident more properly".
Senior Turkish officials had been angered earlier this week by the fact that the media began publishing the names of the suicide bombers before their identities had been officially announced.
Many speculate that the perpetrators of this week's attacks may be targeting largely Muslim but staunchly secular Turkey for its close links to the US, Britain and Israel.
British security chiefs yesterday ordered a further tightening of security arrangements around potential targets for suicide bombings in London and indicated that these levels of security might be sustained for some time after President Bush flies back to the US at the conclusion of his state visit to the United Kingdom later today.
The British security services received intelligence last weekend about a possible al-Qaeda attack on a British target, although not specifically connected to President Bush's state visit.
While they tried to establish if that intelligence related to yesterday's events in Turkey or some other planned action, Scotland Yard sent a 16-strong team of officers from its Anti-Terrorism Branch to join the investigation into the attack on the British consulate, which is constitutionally British sovereign territory.
In London, meanwhile, the Stop The War coalition claimed that as many as 200,000 joined yesterday's "Stop Bush" demonstration, which ended in Trafalgar Square with crowds cheering the symbolic toppling of an effigy of the President. Police estimated the crowds yesterday at 110,000.