Near simultaneous explosions rocked the London Tube and three double-decker buses at the morning rush hour today, leaving up to 50 dead, according to a senior French official. British Sky TV said the attacks killed at least 45 and injured more than 1,000. Some local reports have put the death toll at 90.
The French official, who asked not to be named, came shortly after British police said that at least 33 people died in three of four main attacks on the British transit system.
A group calling itself "The Secret Organization of al-Qaida in Europe" claimed responsibility for the blasts, saying they "were in retaliation for Britain's involvement in Iraq and Afghanistan," AP said. The statement, republished on the site of the German TV news magazine Der Spiegel, could not be confirmed.
First explosion reported at 8.59am London time (17.59 AEST).
At least one London bus blown up in Russell Square, reports of two others in Marylebone and South Kensington.
Explosions reported at Underground stations Edgware Road, King's Cross, Liverpool Street, Old Street, Russell Square, Aldgate East and Moorgate.
London transport system shutdown; Power failure is seen.
At least 45 dead, 1,000 injured.
From the Sydney Morning Herald, with wire reports:
Official statements have confirmed at least 33 dead and 350 injured in a wave of coordinated bomb attacks across the British capital.
Two people were killed in an explosion at London's Aldgate East underground station, police said. 90 were trapped underground and have been evacuated.
Witnesses saw the top ripped off a double-decker bus near Russell Square close to King's Cross train terminal and the twisted wreckage of another nearby.
The shock has damaged the British currency, the pound, which hit two-year lows.
A stunned Prime Minister Tony Blair said the city had been hit by ``barbaric'' terror attacks coinciding with a meeting of Group of Eight leaders in Scotland. Watch Blair video.
In early reports, the BBC said six underground subway stations were hit. The number was later reduced to four total blasts. Police bomb squads and sniffer dogs patrolled other stations as ambulances took the wounded to hospitals on full security alert.
"It is reasonably clear that there have been a series of terrorist attacks in London,'' Blair told reporters, saying he would return to London from the G8 summit.
"Our determination to defend our values and our way of life is greater than their determination to cause death and destruction on innocent people to impose their extremist values on the civilised world,'' he added.
The crisis erupted when emergency services rushed to the Aldgate East underground station where police reported the first blast incident at 8.59am local time (1759 AEST).
A doctor at Aldgate underground station in the east of the financial centre of the city said at least 90 people were wounded at that location alone.
London's police chief Ian Blair said there were indications of explosives at one of the blast sites.
"We are aware that one of the sites certainly does contain indications of explosives,'' he told Sky Television. ``We are concerned that this is a co-ordinated attack.''
London has so far escaped the 2004 Madrid-style bombings blamed on al-Qaeda, and the blasts today left London residents in shock.
People were seen streaming out of one underground station covered with blood and soot. Passengers were evacuated from stations across the capital, many in shock and with their clothes ripped to shreds, witnesses said.
The city's streets were gridlocked and financial markets plummeted as it became increasingly apparent that the blasts were an attack, and not a power surge on the underground train system as had been reported.
The exact cause of the incidents, which occurred one day after London was awarded the 2012 Olympics, was unknown.
Security experts said the apparent attacks bore all the hallmarks of the al Qaeda network.
"If what are looking at is a simultaneous bombing, and it does look like that, it would very certainly fit the classic al Qaeda methodology which centres precisely on that, multi-seated hits on transport and infrastructural targets,'' said Dr Shane Brighton, intelligence expert at the Royal United Services Institute for Defence.
There were people streaming out of Aldgate station covered in blood,'' said Kate Heywood, 27, told the Sydney Morning Herald.There are shards of glass there, it is chaos."
London has suspended all mass transit.
A station official said: ``All the power has gone down. I don't know when it'll come back.'' British officials later said the power situation had been largely restored.
Police sealed off large areas around other underground and mainline rail stations. Firemen donned chemical protection suits before rushing into stations.
Half a dozen people with soot-blackened faces and dishevelled clothes sat on the floor at Russell Square underground station or stood in shock as police cordoned off the area and ambulances crews raced in, one witness said.
The Great Eastern Hotel, hosting a conference on the Israeli economy, was evacuated. Israeli Finance Minister Benjamin Netanyahu cancelled plans to attend the conference; reports later said Israeli intelligence heard advance indications of an attack.
Despite a slump in the British pound, financial markets should recover once the threat has passed and extent of damage is clear, analysts told the BBC. London may be hit harder in the tourism arena.