LONDON (Reuters) – British investigators hunted on Saturday for the suspected al Qaeda bombers who killed more than 50 people on London underground trains and a bus as an Islamist group made a new claim of responsibility for the attacks.

Flowers, notes and appeals for information about missing relatives were piled outside King”s Cross station, where bodies were still trapped deep underground. More than 25 people, of many nationalities and religions, were still unaccounted for.

&#34Barbarism will never kill freedom,&#34 read one note in French. &#34Madrid is with London,&#34 said another.

Police said 49 people were confirmed dead, but emergency staff were still trying to retrieve bodies in one of the subway system”s deepest tunnels two days after the blasts.

British leaders have vowed defiance, and the stoicism of Londoners has been widely praised since the attacks, awakening memories of the capital”s resilience during World War II as the country prepared to mark the 60th anniversary of the war”s end.

&#34This type of terrorism has very deep roots … it is only when you start to pull it up by the roots that you will deal with it,&#34 Prime Minister Tony Blair told BBC radio.

&#34Our revulsion at terrorism is not just a revulsion at the loss of life and innocent bloodshed. It is also a revulsion at trying to create change by these barbaric methods of violence and we will resist that and we are resisting that.&#34

The government says the attacks bear the hallmarks of Osama bin Laden”s Islamic militant al Qaeda network, which was behind the Sept. 11, 2001 attacks on New York and Washington.

A group claiming links to al Qaeda called the Abu Hafs al-Masri Brigades said on Saturday it was behind the blasts and suggested it could strike again. It was the third such claim by an Islamist group since the blasts.

&#34We will not rest until security becomes a reality in the land of Islam and Muslims in Iraq, Afghanistan and Palestine,&#34 it said in an Internet statement.

The group, whose links to al Qaeda are unclear, has claimed authorship of previous attacks in Turkey and Spain.

But intelligence sources have treated its statements skeptically, seeing it as an opportunistic group trying to associate itself to the al Qaeda ”brand”.

Two other groups had already claimed responsibility for the London attacks, saying the blasts were punishment for Britain”s involvement in Iraq and other U.S. allies could be next.

Italy said on Friday its troop withdrawal from Iraq would start as planned in September — and no sooner. Japan said on Thursday it had no plans to withdraw its troops.

&#34There isn”t a single country in Europe that can consider itself immune to this type of risk,&#34 European Union Counter-Terrorism Coordinator Gijs de Vries said in Brussels.

U.S. officials forced a flight from Paris to Chicago with 291 passengers on board to return to France late on Friday while it checked the list of passengers, without giving a reason.

Police have made no arrests but officials have gradually released more details about the bombings, saying each of the bombs was believed to have contained up to 10 lbs (4.5 kg) of explosives and could have been carried around in backpacks.

A leading forensic scientist said it could takes months or even longer to identify all the people killed.

&#34The biggest problem will be the closer you get to the impact explosion site, the more fragmented will be the remains, so the identifications becomes more difficult,&#34 said Professor Sue Black, a forensic expert at Dundee University.

London”s creaking transport network slowly resumed service on Friday although parts of the underground rail network, which carries 3 million people a day, will be disrupted for weeks.

Theatres reopened on Friday evening, but restaurant and bar owners said business was unusually quiet.

The World Travel & Tourism Council estimated that visitor arrivals to Britain might decline by more than half a million or about 2 percent in 2005 from an earlier expected 31 million.

But many visitors said they would not change their plans.

&#34My family were already visiting before the bombs. We are not going to cancel anything,&#34 said Sukrit Ngamdumrongkiat, 21, a student from Thailand showing three relatives around. &#34We are upset, but don”t think it will happen again. It is very sad.&#34

Many of Britain”s 1.6 million Muslims mourned the dead and condemned the bombers at Friday prayers but expressed fears of retaliation. The Muslim Association of Britain and groups opposed to the Iraq war plan a vigil for victims.

&#34Some people will try to instigate anger against Muslims and try to blame us for what happened,&#34 said Mohamed Sawalha, who led Friday prayers” sermon at London”s Finsbury Park mosque.

London police chief Ian Blair said the authorities were in touch with Muslim leaders and those of other faiths to protect symbolic buildings. The government and religious leaders called for a calm response to the bombings after holding talks.