LONDON — Armed with new intelligence from Pakistan suggesting al-Qaida plotted to attack London's Heathrow airport, police questioned a dozen terror suspects Thursday and announced the arrest of a man wanted on terrorism charges in the United States.

But at Heathrow, a man reading a newspaper with the front-page headline Heathrow Bomb Plot told a reporter he was unaware of any security scare. And a woman headed to Boston shrugged off the threat, saying, "I've just got to get on with it."

Intelligence officials in Pakistan told The Associated Press they found images of Heathrow and other sites on the computers of two arrested al Qaeda fugitives, and that this information was passed to British officials.

Police, however, would not say if this information helped lead to the arrests of the 12 suspected terrorists earlier this week in Britain. Among the 12 was a senior al Qaeda member, known as Abu Eisa al-Hindi or Abu Musa al-Hindi, who media reported was involved in plotting against Heathrow.

On Thursday, police gained court approval to continue questioning until Sunday afternoon. Further extensions up to a total of two weeks are possible.

Police also said they had arrested a British man, Babar Ahmad, wanted on terrorism charges in the United States, and that anti-terror officials were searching three "residential premises" and one business in southwest London on behalf of U.S. authorities.

Ahmad, 30, is accused in the United States of trying to raise funds for "acts of terrorism in Chechnya and Afghanistan" from 1998 through 2003, according to the U.S. extradition warrant. His detention was not believed to be linked to the arrest of the 12 on Tuesday.

Earlier, Peter Hain, leader of the House of Commons, told British Broadcasting Corp. radio that those detained Tuesday "are important arrests" but declined to comment on reports of a plot against Heathrow.

"If we had evidence of a specific threat, then we would tell everybody," he said. "Now the situation is not that at this stage."

A Heathrow spokeswoman said airport authorities had not heard anything from the government "to suggest the threat level to Heathrow has increased in recent weeks."

At the airport, Europe's busiest, many took the news in stride.

Mohammad Iqbal, 32, was flipping through The Sun newspaper and apparently overlooking the banner headline on the front page, said he was unaware of any alert.

"I'm not frightened," he said. "When my time is up, it is up."

Cuong Vuong, 24, a student headed to Singapore, said he had heard about the reported plot on the radio. "I am a little bit frightened," he said.

Barbara Asell, 60, a British woman flying to Boston to visit her son, said the scare was "one of those things you have no control over. I have no control over what happens at Heathrow, and I've just got to get on with it."

Maps, photographs and other details of possible targets in the United States and Britain were found on computers belonging to Ahmed Khalfan Ghailani, a Tanzanian indicted for his role in the 1998 bombings of U.S. embassies in East Africa, and a Pakistani computer expert identified as Mohammed Naeem Noor Khan, said two Pakistani officials, who spoke on condition of anonymity.

A Lahore-based intelligence official involved in the investigation following the July 13 arrest of Khan said his computer contained photographs of Heathrow airport, as well as pictures of underpasses that run beneath several buildings in London.

He said, however, that he was unaware of any information from Khan that led directly to the arrests Tuesday in Britain.

Pakistani Interior Minister Faisal Saleh Hayyat told reporters the arrests in Britain were not based on "specific information" from Pakistan.

"There is no specific information that we gave to Britain," Hayyat said. "What we do is that whenever we feel the need that certain information could be relevant or of use for our coalition partners, we do exchange information and we do share information and intelligence."

Hayyat told Britain's Channel 4 news that talk of a Heathrow plot was "purely speculative."

"We certainly do not have any specific information which would back up that suggestion," he said.

The CIA provided information that contributed to the detention of al-Hindi, as well as information that led the Pakistanis to detain Khan.

The Washington Post and several British newspapers reported that al-Hindi, using the codename Bilal, was in touch with Khan and had been plotting an attack on Heathrow.

Police and the Home Office refused to comment on the reported Heathrow plot or whether al-Hindi was among the 13 suspects they arrested on suspicion of involvement in the "commission, preparation or instigation of acts of terrorism." One man has since been released. Police haven't said what they suspect the men of doing.

Heathrow has been at the centre of terrorism fears before.

In February 2003, the government deployed tanks and troops there after police warned that al Qaeda might try attacking London. Officers searched cars, vans and boats in towns under the airport's flight path. Police even considered closing the airport.

In March, 1994, the Irish Republican Army fired a dozen mortar shells at Heathrow in three attacks within days of each other. None exploded, but flights were severely disrupted.

News reports in Italy on Thursday said security had been increased at Rome's Leonardo da Vinci airport following a series of threats by an al Qaeda-linked group against the country, an important U.S. ally.

Heightened measures included controls at check-in desks and baggage scanners, and patrols by sniffer dogs and plainclothes security officials, the ANSA and AGI news agencies said.