The British Prime Minister, Tony Blair, has promised one of the most 'vigorous and intensive' police manhunts the UK has ever seen to bring the perpetrators of the London bombings to justice.
Speaking in the House of Commons this afternoon, Mr Blair said it seems probable that the bombs were planted by Islamist extremist terrorists of the kind responsible for the outrages in New York and Madrid.
The prime minister also said he knew of no intelligence that would have allowed the security services to prevent the atrocities which killed at least 52 people.
It comes after the Conservative Party called for an inquiry to see if anything could have been done to prevent the attacks.
Mr Blair also called for a two-minute silence on Thursday to allow the country unite briefly in its grief, adding that 7 July would always be remembered as a day of sadness for Britain.
Bombings an attack on civilised world: Bush
US President George W Bush said last Thursday's bombings in London were an attack on the civilised world.
He said the only course of action against such attacks was to take the fight to the enemy until that enemy was defeated.
Mr Bush said the US and Britain would stand together against what he called the murderous ideologies of the 21st Century.
Rescue work continues
In London, rescue workers are continuing to battle against horrendous conditions in an Underground tunnel between King's Cross and Russell Square and have not ruled out finding further remains.
Sources said the final death toll could be slightly higher than 52 but was not expected to be significantly higher than that.
Only two victims have so far been formally identified. They are mother-of-two, Susan Levy, 53, from Hertfordshire who died in the explosion at King’s Cross, and cleaner Gladys Wundowa, 51, who died in the bus bombing in Tavistock Square.
Concern over delay in identifying bodies
The Irish father of one of the missing people in Thursday's attacks has criticised the authorities for taking so long to identify bodies.
Seán Cassidy, originally from Swanlinbar in Co Cavan, said he believed his 22-year-old son, Ciaran, who holds an Irish passport, died in the attack on King's Cross Station.
He told RTÉ Radio One’s Morning Ireland programme he was only contacted by the authorities yesterday, and had not been given any other information.
Home Office Minister Hazel Blears has defended the pace of identifying victims of the attacks. She said: 'Identification is complex. It is absolutely vital we get this right. You can imagine the implications of getting it wrong.'
People in London returned to normal working hours this morning, four days after the bomb attacks. Business leaders said it was important for people to return to work to avoid damage to the country's economy.
As the investigation into the bombings continues, police say they are encouraged by the response to their appeal to the public to come forward with photographic images taken in London on Thursday.
Meanwhile, three men arrested under British anti-terror laws at Heathrow Airport yesterday have been released without charge. A police spokesman said the arrests had not been made as a result of information about the London bomb attacks.
Livingstone takes Tube to work
London Mayor Ken Livingstone today took the Tube to work and sent the message that people should carry on as normal. Mr Livingstone boarded a packed commuter service from Willesden Green station to London Bridge for work at City Hall.
As he entered the Tube station, he said: 'We are going to work. We carry on our lives. We don't let a small group of terrorists change the way we live.' Asked if people should try to forget about last week's bomb attack, he said: 'We carry on our lives. I don't think we ever stop thinking about last week.'