A security clampdown

LONDON -- Air travelers faced delays and heightened security measures after British police yesterday said they foiled an audacious plot by would-be suicide bombers to blow up as many as 10 US-bound airliners with liquid explosives smuggled onboard in soft drink bottles.

Authorities in Britain and the United States raised security alert levels and imposed the strict security rules, snarling international flights on both sides of the Atlantic throughout the day. Britain banned all carry-on bags, and the United States barred liquids and gels and other containers from hand luggage. The bans are in place indefinitely.

US counterterrorism officials said the alleged plan involved flights from Britain to major destinations that could have included Boston, New York, Washington, D.C., Chicago, and Los Angeles.

In a series of hastily arranged overnight raids in London and elsewhere in Britain, police arrested 24 suspected Islamic radicals, many of Pakistani descent.

British and American law enforcement officials said the investigation was pointing to Pakistan as the origin of the alleged plot. Like the four suicide bombers who blew up three trains and a bus in London last year, most of the suspects arrested yesterday are believed to be British-born Muslims who became radicalized over what they perceive as the West's crusade against Islamic countries.

Early today, the Bank of England froze the assets of 19 people, naming them as among those arrested yesterday in connection with the case. Most on the bank's list were London residents, and many bore Muslim names. Scotland Yard had no immediate comment on the bank's statement.

The oldest person on the bank's list is 35. The youngest is 17.

Investigators said an Islamic militant who was arrested in Pakistan last month for the killing of a US diplomat and three others may have helped British authorities foil the alleged plot, which may have been hatched and paid for in Pakistan.

Pakistan authorities detained up to three other people several days ago in connection with the plot, US officials said.

``Put simply, this was intended to be mass murder on an unimaginable scale," said Paul Stephenson , deputy commissioner of the Metropolitan Police of London, whose antiterrorism branch and MI5, the British intelligence service, coordinated the raids, which stretched to Birmingham, about 100 miles northwest of London.

FBI Director Robert S. Mueller III said the alleged conspiracy bore ``all the earmarks of an Al Qaeda plot." While he and other officials said they did not have any evidence linking the alleged plot directly to Al Qaeda, President Bush said the arrests ``are a stark reminder that this nation is at war with Islamic fascists."

It was unclear when the alleged attacks were to take place, but the arrests were made sooner than authorities had expected. The Associated Press quoted a US intelligence official as saying the suspects planned a dry run within two days and the attack days after that. The AP also quoted a federal law enforcement official in Washington as saying that at least one ``martyrdom tape" was found during the raids. Such tapes are an earmark of Al Qaeda.

According to one British law enforcement official, police decided to move in after some of the suspects under surveillance disappeared, triggering fears that the final stages of the attack were underway.

ABC News reported that some of the suspects recently traveled to Pakistan to obtain the money needed to pay for the tickets for the alleged bombers, who had been looking into flights between the United States and Britain on three US carriers -- American, United, and Continental. The suspects planned to board the flights in teams, mix their lethal cocktail , then explode them somewhere over the Atlantic, officials said.

Britain's home secretary, John Reid, who is in charge of national law enforcement, said the plot's ``main players had been accounted for," but other British law enforcement officials said further arrests are expected, and some acknowledged that it is not yet known how many alleged conspirators remain at large.

Underscoring the abrupt decision to make the arrests, Prime Minister Tony Blair , who was briefed regularly about the ongoing investigation, had left for vacation in the Caribbean last weekend.

Peter Clarke, chief of the Metropolitan Police antiterrorism branch, said that his officers had been monitoring the ``spending, travel, and communications" of a ``large number of people" for some time.

``The alleged plot has global dimensions," Clarke said. ``The investigation reached a critical point Wednesday night when the decision was made to take urgent action in order to disrupt what was being planned."

Speaking in Washington, Homeland Security Secretary Michael Chertoff said US authorities had been alerted to the British probe within the last two weeks, and that the alleged plot was ``in the final stages of planning before execution." He said officials believed that the suspects planned to bring ``on board a number of different components of a bomb . . . each one of which would be benign but when mixed together would create a bomb."

US officials sent out a memo yesterday warning law enforcement officials nationwide that the suspects had planned to use peroxide-based liquid explosives that could be triggered by a flame, friction, or an electronic charge produced by something as benign as a cellphone.

Chertoff said that there was ``currently no indication of any plotting within the United States." He said federal air marshals are being dispatched to the United Kingdom to help beef up security.

About 106 flights per day travel between Britain and the United States, and yesterday's arrests led to chaos as canceled flights stranded passengers and the new security measures caused huge delays.

``It's a bummer," said Alicia Ross of Melrose, who along with her husband, Ian Arnold , and son, Spencer, was waiting for a flight back to Boston at Heathrow Airport. Still, Ross said she felt safer in London than Boston.

The alleged plot mirrored one planned by Al Qaeda 12 years ago to use liquid explosives to simultaneously blow up airliners over the Pacific Ocean.

Officials in Pakistan, meanwhile, said their intelligence agents had developed the tip that alerted British police to the alleged plot when they arrested an Islamic extremist on the Afghanistan-Pakistan border several weeks ago, AP reported.

The names released by the Bank of England yesterday were: Abdula Ahmed Ali, Cossor Ali, Shaza Khuram Ali, Nabeel Hussain, Tanvir Hussain, Umair Hussain, Umar Islam, Waseem Kayani, Assan Abdullah Khan, Waheed Arafat Khan, Osman Adam Khatib, Abdul Muneem Patel, Tayib Rauf, Muhammed Usman Saddique, Assad Sarwar, Ibrahim Savant, Amin Asmin Tariq, and Shamin Mohammed Uddin.

Kevin Cullen reported from Boston; Alana Semuels from London. Farah Stockman, Charlie Savage, and Bryan Bender of the Globe's Washington bureau contributed to this report.