London bombings: Police updates

A massive intelligence operation is under way after the series of bomb attacks which killed at least 50 people in central London.

At a press conference on Friday, Scotland Yard Commissioner Sir Ian Blair said police had an "implacable resolve" to track down those responsible.

Here is a summary of the main points of the inquiry and recovery operation to have emerged.

More than 50 people are so far known to have died in the blasts, on three trains and a bus. The bus bomb claimed 13 lives

There were 350 casualties treated at the scene, while a further 350 were taken to hospital. A hundred people were detained overnight, 22 of whom are in a serious condition. One person died in hospital

People from Sierra Leone, Australia, Portugal, Poland and China as well as the UK were caught up in the blasts

Sir Ian said the timing of the attacks meant it could not have been carried out by just one person and there was no evidence it was suicide bombings

London mayor Ken Livingstone said he would be using the tube to get to work on Monday and he urged Londoners to do the same

He praised the work of the emergency services saying: "Everything we had planned for on this day we knew would happen, worked like clockwork."

Over 104,000 calls have been received by the Scotland Yard casualty bureau

There are still an unknown number of bodies trapped in the wreckage of the Tube train hit in a tunnel between King's Cross and Russell Square. The instability of the tunnel is hampering the recovery operation, but teams have reached the bombed carriage

The nature of the explosion on the bus is also making it difficult for search teams to be accurate on the death toll, police said

Each device was likely to have contained less than 10lbs of explosives

The devices were probably of a size which would fit into a rucksack, police believe

The Liverpool Street explosion happened 100 yards into a tunnel and the device was in the third carriage of the train.

In the explosion between King's Cross and Russell Square the bomb was in the first carriage

The device in the Edgware Road blast was in the second carriage

It is believed the bombs on the Tube trains were all on the floors of the carriages at the time of their detonation

Sir Ian said police are still not sure exactly where the bomb on the bus was placed

He said there was no proof that the bus bomb was the work of a suicide bomber but at this stage "nothing could be ruled out"

There were two other "controlled explosions" carried out by Met experts on Thursday but no other bombs were found

Police considered suspending the mobile phone network in the wake of the attacks but decided such a move would have damaged public confidence

Early indications suggest the attacks were carried out by al-Qaeda, Sir Ian said

He dismissed reports that the bombings were the work of a terror cell based in the Midlands as "pure speculation"

Investigators are sifting through hundreds of hours worth of CCTV footage from a huge number of locations and collecting forensic evidence from the bomb sites

Metropolitan Police staff have been "overwhelmed" by help from other forces in Europe and the US

Sir Ian said it is "likely" that a terrorist cell is still active in the UK and warned people to be vigilant

"This is a national issue, not just for London. All of the police forces in the UK are taking steps to increase their footsteps on the ground and to work with communities," he said

Anyone with information is urged to contact the anti-terrorist hotline on 0800 789321