Britain's Prime Minister Tony Blair says last week's terrorist attacks in London were probably carried out by Islamist extremists.
Speaking to parliament, Mr. Blair declined to give details on an ongoing police investigation. But he praised the work of police and emergency services after the blasts on underground trains and a double-decker bus.
Opposition leader Michael Howard said he hopes the government in coming weeks will try to uncover possible security flaws exploited in the attacks.
Meantime, police say the confirmed number of dead in the bombings has risen to 52, with about 700 people injured.
Forensic experts say it may be weeks before all of the victims are publicly identified.
London Mayor Ken Livingstone became the first to sign a book of condolences for the victims, writing "the city will endure."