Eleven of the men who hijacked U.S. airliners on Sept. 11 may have traveled this year to the United Kingdom for meetings or training, including a possible strategy session that drew five of the terrorists in June, Scotland Yard said today.

As the attacks reverberated far beyond ground zero, Dutch police detained an Iraqi man suspected of belonging to a radical Islamic network planning attacks, and Spanish authorities arrested six Algerians they said were "directly linked" to suspected terrorists arrested in Belgium and the Netherlands two days after the bombing.

In the United States, a federal magistrate ordered two men held without bond on minor charges, telling an Alexandria, Va., courtroom that these are not times of "business as usual." Police in three states, meanwhile, arrested at least nine men accused of falsely obtaining licenses to drive trucks carrying hazardous materials.

Britain, which has a large Muslim population, relatively open borders and broad freedom for political groups, has long served as a base for militant Islamic fundamentalist groups, including the network of Osama bin Laden, the exiled Saudi militant believed by the Bush administration to be the architect of the Pentagon and World Trade Center attacks.

London was the base of operations for Khaled al-Fawwaz, said to be a top bin Laden lieutenant and a recruiter of young men for al Qaeda military units. Al-Fawwaz and two of his associates, Ibrahim Eidarous and Adel Abdul Al-Bary, have been jailed for three years here, after their indictment in New York on charges of helping plan the 1998 bombings of two U.S. embassies in East Africa.

Zacarias Moussaoui, arrested in Minnesota last month after flight school officials became suspicious of his desire to learn only to steer a Boeing aircraft -- not practice takeoffs or landings -- once lived in London, where police have searched his former home. French intelligence authorities told the FBI that Moussaoui is a member of bin Laden's network.

British authorities said little today about the 11 hijackers' visits to the United Kingdom, which were first reported by the Times of London. They said the FBI asked for their help in reconstructing their local activities, a task that Scotland Yard's assistant commissioner, David Veness, called a "top priority."

Authorities in Spain said the suspects under arrest today financed themselves by falsifying documents -- including passports and airplane tickets -- and by creating fake credit cards. Police seized state-of-the-art equipment for forging documents.

In the United States, court documents unsealed today showed that state and federal officials have known for more than a year about an alleged truck-licensing scam in Pennsylvania involving 20 men, nine of whom were arrested in Michigan, Missouri and Washington. They became enmeshed in the terror probe on Tuesday because of fears about attacks using hazardous materials.

Attorney General John D. Ashcroft told lawmakers Tuesday that "our investigation has uncovered several individuals, including individuals who may have links to the hijackers, who fraudulently have obtained or attempted to obtain hazardous material transportation licenses."

Justice Department spokeswoman Susan Dryden said none of the nine arrested today have any known links to the hijackers. But the FBI has issued alerts to the trucking industry and has ordered its field offices to check whether any of the hundreds of people being sought for questioning in the terror probe obtained hazardous materials licenses.

The fear among law enforcement officials is that such a license could be used as part of a plot involving dynamite, radioactive waste or dangerous chemicals. But officials also cautioned today that, given that nearly all the charges stem from one apparent scam, the men could simply be otherwise law-abiding immigrants who cut corners to get lucrative trucking licenses.

In Alexandria, a District man accused of helping several hijackers obtain Virginia licenses was ordered held without bond today by U.S. Magistrate W. Curtis Sewell. The suspect, Herbert Villalobos, said he met five of the hijackers for the first time last month in a state motor vehicle department parking lot.

Defense attorney Mike Lieberman noted at the hearing in U.S. District Court in Alexandria that the crime was minor and argued that his client, a legal immigrant from El Salvador, deserved to be released on bond. He said, "There's no reason to treat this defendant differently because of what somebody else did, as horrible as it was. There's no evidence that he had anything to do with it."

Assistant U.S. Attorney John Morton said the government has no direct evidence to show that Villalobos knew about the attack plans, but the prosecutor also said that authorities believe Villalobos has more information than he has disclosed.

Sewell ordered Villalobos held behind bars.

"One of the unspoken issues today is, after the events of September 11th, is it going to be business as usual?" Sewell said. "I suspect not. The defendant, either wittingly or unwittingly . . . but certainly unlawfully, contributed in some way to the horrific acts."

The FBI is searching for a man -- publicly known only as "Jalali" -- who may know of a terrorist threat that forced former defense secretary William S. Cohen to cancel a trip last year to an American air base in Incirlik, Turkey, according to federal officials and an FBI affidavit.

During a search last week of a Detroit home, FBI agents seized a day planner that refers to the "American Defense Minister" and crude sketches of aircraft and runways that appear to correspond to the Incirlik base, which is used by pilots enforcing the no-fly zone over northern Iraq.

Cohen canceled his trip to the base last year after "learning of a credible threat against him," a former U.S. Department of Defense official said.

Agents found the day planner after going to an apartment in southwest Detroit in search of Nabil Al-Marabh, a former Boston cabdriver who is a suspected associate of bin Laden. Agents also seized false documents that bore the name "Michael Saisa." Authorities said the photo on the passport may actually be that of Jalali, who apparently had lived in a previous apartment with two of the three men arrested last week. The men, according to authorities, said they had kept the documents in case he returned for them.

In other developments today:

* The Securities and Exchange Commission took the unprecedented step of asking the entire securities industry to search for records of business dealings with suspected terrorist groups. The agency asked firms to find out whether they ever had accounts or made trades with anyone on the FBI's list of 19 suspected hijackers or the list of 27 individuals and groups President Bush named this week as financiers of terrorism.

* SunCruz Casinos LLC has turned over to the FBI surveillance pictures and other records from two Florida gambling cruises on Sept. 5. In both cases, a company official said, there was a passenger who looked similar to one of the hijackers, and the name given by the passenger was either the same or similar to the hijacker's name.

* U.S. Attorney Mary Jo White announced that San Antonio radiologist Al-Badr Al-Hazmi, arrested by the FBI on a material witness warrant, "voluntarily answered all questions put to him" before his release. She said he is "not a subject of this investigation."

* Federal aviation officials no longer believe that accomplices of the hijackers made phony bomb threats to confuse air traffic controllers on Sept. 11. Sources said reports of multiple threats were apparently the result of confusion during the early hours of the investigation and miscommunication in the Federal Aviation Administration. FAA officials did say today, however, that there was a telephoned threat on Sept. 11 that a plane would crash into the FAA air traffic center in Nashua, N.H.

Lengel reported from Washington. Staff writers Justin Blum, David Fallis, Brooke A. Masters, Don Phillips, Lois Romano, Peter Slevin and Carol Vinzant, and special correspondent Pamela Rolfe in Madrid, contributed to this report.

Outside Lakenheath air base in Britain, security personnel guard a truck that contained several stowaways.In Spain, Hocine Khouni was one of six Algerians held on suspicion of being "directly linked" to terrorists.In Alexandria, Herbert Villalobos was ordered held on charges of helping hijackers obtain Virginia licenses.