LONDON, July 9: Police hunting for suspected Al Qaeda bombers who killed more than 50 people in London said on Saturday three of the blasts were almost simultaneous, making it more likely they were detonated by timers than suicide bombers.

They said a fourth bomb that blew up a bus almost an hour later was probably left in a bag and not triggered by a suicide bomber, but did not speculate why it went off so long after the three blasts on underground trains in the space of 50 seconds.

Investigators were struggling in extreme heat to retrieve bodies still trapped underground two days after the attacks, and anxious relatives were frantically looking for loved-ones missing since the rush-hour blasts on Thursday morning.

Police, who have made no arrests, said they were looking for no specific individuals and that the bombs were made of high explosives, not home-made materials.

A third group claimed responsibility for the blasts, which British ministers said bore all the hallmarks of the Al Qaeda network.

“All three bombs on the London Underground system actually exploded within seconds of each other around 8.50 in the morning,” Scotland Yard deputy assistant commissioner Brian Paddick told a news conference.

“Bearing in mind these were almost simultaneous, we think within 50 seconds of each other, maybe that lends more towards timing devices more than people actually with the bombs, manually detonating. But we are not ruling out either of those possibilities.”

Police had previously thought the three blasts were spread over nearly half an hour, but revised their information in the light of new technical data and witness statements, he said.

ODD ONE OUT: The fourth bomb exploded on a bus near Euston railway station at 9.47am.

“The most logical explanation is that one of the terrorists was unable to board an underground train — probably because of the rapid closure of the system — and ended up with a primed bomb and no target,” said Dominic Armstrong, head of research and intelligence at security group Aegis Defence Services.

“In the circumstances, it seems understandable that he should seek another similar target quickly.”

Flowers, notes and appeals for information about missing relatives piled up outside King’s Cross station, where bodies were still trapped deep underground. About 30 people, of many nationalities and religions, were still unaccounted for.

“Barbarism will never kill freedom,” read one note in French. “Madrid is with London,” said another. Train bombings linked to Al Qaeda killed 191 people in Madrid last year.

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. One expert likened the conditions to working in a ‘fetid tunnel’.

Police say there could be more attacks and security experts suggest would-be attackers could opt to kill themselves and take as many victims with them as possible if confronted.

NEW CLAIM: A group which said it had 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 a group since the blasts.

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

The group has said it was behind previous attacks in Turkey and Spain. But intelligence sources have treated its statements sceptically, seeing it as an opportunistic group trying to associate itself with Al Qaeda.

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

Parts of London’s transport network, which carries three million people a day, could be disrupted for weeks, officials said. —Reuters