London Investigators on three continents worked to fill in the full, frightening picture Friday of a plot to blow U.S. jetliners out of the Atlantic skies, tracking the money trail and seizing more alleged conspirators in the teeming towns of eastern Pakistan.
One arrested there, a Briton named Rashid Rauf, is believed to have been the operational planner and to have connections with al-Qaida in Afghanistan, Pakistani and U.S. officials said.
British and Pakistani authorities have arrested as many as 41 people in the two countries in connection with the alleged suicidal plan, broken up by British police this week, to detonate disguised liquid explosives aboard as many as 10 planes bound from Britain to the United States.
"The terrorists intended a second Sept. 11," said Frances Fragos Townsend, White House homeland security adviser.
New information underlined how close they were to mounting attacks.
After the first arrests in Pakistan some days ago, word went from Pakistan to the London plotters to move ahead quickly, a message intercepted by an intelligence agency, a U.S. official disclosed on condition of anonymity. That prompted British police to move in on the conspirators, long under watch.
British Home Secretary John Reid told reporters officials were confident the main suspects in the plot were in custody. But authorities "would go where any further evidence takes us," he said.
"I think it's pretty clear that in this case, we don't have everybody," Townsend told The Associated Press in Washington.
The British government released the names of 19 of the 24 arrested in Britain - many apparently British Muslims of Pakistani ancestry - and froze their assets. One of the 24 detainees later was freed.
The record of financial transactions, along with telephone and computer records, may help investigators trace more people in the alleged plot.
"Think of it as a river - you look upstream to find the source, and downstream to find out where the money is going," said Cliff Knuckey, former chief money laundering investigator for Scotland Yard.
No major U.S. links
American authorities were looking for any U.S. links in the conspiracy. Hundreds of FBI agents checked possible leads the past few weeks, including what two U.S. counterterrorism officials said, on condition of anonymity, were calls the British suspects placed to several U.S. cities.
But the U.S. homeland security secretary said Friday nothing significant had emerged. "Currently, we do not have evidence that there was, as part of this plot, any plan to initiate activity inside the United States or that the plotting was done in the United States," Michael Chertoff said.
Threat level critical
Britain kept its threat assessment level at "critical," indicative of an imminent attack. Extraordinary security measures continued at British airports, although the backlog of passengers eased from Thursday's chaotic conditions, when hundreds of flights were canceled.
At Heathrow, Europe's busiest airport, about 70 percent of flights operated Friday, but many people turned around and headed home after an announcement that a raft of flights had been canceled, including British Airways services to San Francisco and Los Angeles.
At U.S. airports, airlines were recruiting more baggage handlers as U.S. travelers - facing new rules banning almost all liquids from carry-on luggage - adapted by checking bags they normally would have carried aboard. American passengers faced a second level of security checks starting Friday, with random bag searches at boarding gates.
The alleged terrorists were planning to assemble their bombs aboard the aircraft, apparently with a peroxide-based solution disguised as beverages or other harmless-seeming items, and using such electronic equipment as a disposable camera or a music player as a detonator, two U.S. law enforcement officials told The Associated Press.
A U.S. intelligence official said they planned to deploy a couple of attackers per plane, and the two dozen plotters didn't all know one another - a typical security measure in terror groups.
London's Evening Standard reported the plotters apparently chose next Wednesday as a target date, since they had tickets for a United Airlines flight that day, as well as ones for this Friday, apparently a test-run to see whether they could smuggle chemicals aboard in soft-drink containers.
The paper didn't report the flight's destination, but United has flights from Heathrow to New York, Washington, Chicago, Los Angeles, San Diego, San Francisco and Seattle.
The British say their inquiry began months ago - prompted by a tip from within the British Muslim community after the bloody July 7, 2005, terror bombings of the London transit system, The Washington Post reported.
There were signs preparations stepped up recently. One of the houses raided by British police this week had been bought last month by two men in an all-cash deal, in a neighborhood of $300,000 houses, neighbors reported.
Pakistani officials said British information led to the first arrests in Pakistan about a week ago, of two British nationals, including Rauf, called a "key person" by the Pakistani Foreign Ministry.
Pakistan's interior minister, Aftab Khan Sherpao, said Rauf has ties with al-Qaida and was apprehended in the Afghanistan-Pakistan border area. The Foreign Ministry in Islamabad spoke of "indications" of a link between Rauf and al-Qaida in Afghanistan.
On an unspecified date, Pakistani authorities also arrested five Pakistanis as alleged 'facilitators" for the Britons in the major cities of Lahore and Karachi. An intelligence official in Islamabad said 10 other Pakistanis had been arrested Friday in the district of Bhawalpur, about 300 miles south of Islamabad near the Indian border.
Possible al-Qaida tie
Pakistan is both a key U.S.-British ally in the antiterror campaign, and a hotbed of Islamic radicalism and likely hiding place for al-Qaida leader Osama bin Laden.
"I am 120 percent convinced there's a link" with al-Qaida, Louis Caprioli, a former top French counterintelligence official, said of the trans-Atlantic bombing plot. "Was it al-Qaida who contacted them, or vice versa? Only the investigation will be able to tell."
Scotland Yard didn't identify the lone detainee released Friday from among 24 arrested in London, the town of High Wycombe 35 miles west of London, and the central city of Birmingham.
The 19 identified ranged in age from 17 to 35, had Muslim names and appeared to be of Pakistani descent, although many were born and all reared in Britain.
One not on the list of 19 names was believed to be a young woman in her 20s with a 6-month-old baby. At least three people among the suspects were converts to Islam. It was unclear how the alleged plotters met, or who the ringleader was, although suspicion fell on the only one identified who is over 30 - Shamin Mohammed Uddin, 35, of east London.
A teenage neighbor of suspect Assad Sarwar, 26, who lived with his parents in High Wycombe, said Sarwar had become increasingly strident after the London transit bombings, in which four suicide bombers killed 52 other people. "He started talking about terrorism and acting like it's OK to blow up people," said Nawaz Chaudhry, 17.
At least one "martyrdom" tape, the type left by suicide bombers, was found in the British raids, a U.S. law enforcement official said.
Under Britain's toughened antiterrorism laws, suspects can be held for up to 28 days without charge. On Friday, detention orders for 22 suspects were extended through Wednesday. The 23rd suspect, still in custody, will have a detention extension hearing Monday.