Police patrols increase to ease fear in London

LONDON -- Thousands of police took to the streets to reassure a jittery public yesterday, four weeks after suicide bombers struck the British capital. Meanwhile, Al Qaeda warned of more attacks.

Underground rail stations swarmed with police, many of them armed, as millions of commuters headed into work.

''It is certainly a very big police operation," said Deputy Chief Constable Andy Trotter. ''We are out there to reassure Londoners and also to deter any further attacks."

Al Qaeda's second in command Ayman al-Zawahri issued a warning to Britain in a new video aired yesterday.

''Blair's policies will bring more destruction to Britons after the London explosions," Zawahri, Osama bin Laden's deputy, said in a tape aired by Al Jazeera television.

Prime Minister Tony Blair, President Bush's closest ally, has consistently rejected the idea that Britain's involvement in the war in Iraq is linked to the attacks on London last month.

Yesterday, the Piccadilly underground railway line was fully operational for the first time since four British Muslim suicide bombers killed 52 people on three trains and a bus on July 7.

The New York Times reported, that intelligence information gathered recently suggested that another team of bombers might be planning a synchronized attack in London or elsewhere in Britain. The Times cited a senior American police official saying that he had been told by his counterpart in Scotland Yard that the information was ''specific enough to worry them that something is coming."

The Times cited an unnamed senior intelligence official based in Europe as saying: ''The British have told us -- they feel sure there will be a third wave of attacks."

Offering an intriguing glimpse into the investigation, New York police chief Raymond Kelly said on Wednesday that the bombs were made from simple ingredients like hair bleach. Three of them were set off by mobile phones, he said.

''It's more like these terrorists went to a hardware store or some beauty supply store," Kelly said.

He said the explosives were stored in refrigerators and then shipped in coolers to a railway station outside London where the bombers took a train to the capital.

His briefing, partly based on information from New York officers sent to London to monitor the police inquiry, was the first detailed account of the methods used by the bombers.

In another wave of attacks two weeks after the first, four bombs failed to detonate and, after the biggest manhunt in British history, four suspects were arrested, including one seized in Rome.

The police operation after the attacks -- one of the biggest ever seen in the British capital -- is costing an extra 500,000 pounds ($890,000) a day, officials have said.

Undercover officers mingled with commuters trying to spot would-be bombers while the massive coverage by uniformed officers was designed to make people feel safer.

Nerves in London are still frayed. Panicked passengers smashed windows and jumped from the upper deck of a bus on Tuesday after a small fire developed, apparently accidentally.

A 23-year-old man arrested after the failed July 21 attacks has been charged under British terrorism laws with hindering the police investigation by protecting a possible suspect.

Ismael Abdurahman, who appeared in court yesterday and was remanded in custody until Aug. 11, is the first person to be charged as part of the investigation into the attacks but is not one of the four men suspected of trying to set off the bombs.

British police believe all four men they had been hunting over the July 21 attacks on three underground trains and a bus have been captured.

Police charged two women under antiterrorism laws yesterday for failing to give police information after the July 21 attacks.

Police said they would appear at the capital's Bow Street Magistrates' Court today charged under the Terrorism Act 2000.