Meanwhile, Britain's prime minister called for increased security for a weekend that includes Wimbledon, a Live Earth concert, and the second anniversary of the 2005 transit attacks that killed 52 people.

"From what I know, we are getting to the bottom of this cell that has been responsible for what is happening," Prime Minister Gordon Brown said.

The FBI confirmed a report in yesterday's Inquirer that two of the seven doctors tied to last week's attacks had contacted a Philadelphia-based service that certifies foreign-trained doctors to work in the United States. One of them is neurologist Mohammed Jamil Asha, a Jordanian, the FBI confirmed.

The second doctor, sources said, is Mohammed Haneef, an Indian detained last week as he tried to leave Australia.

Neither doctor ever visited the United States, the sources said.

After the attempted attacks in Britain last week, FBI agents in Philadelphia visited the Market Street offices of the nonprofit organization that is the national clearinghouse for foreign-trained doctors seeking graduate work - the Educational Commission for Foreign Medical Graduates.

Agents found records related to applications by Asha and Haneef, officials said. The education commission verifies foreign doctors' credentials and administers required exams. It does not issue visas.

Stephen Seeling, the commission's vice president, who was visited by FBI agents this week, said he could not comment on any applicant.

Asha, who graduated from medical school in Jordan in 2004, applied to take the U.S. graduate tests last year, FBI spokeswoman Nancy O'Dowd said. Sources said Haneef also applied last year.

Apparently, neither doctor took the entrance tests, officials said.

Asha, 26, and his wife, Marwa, 27, a medical technician, were arrested by British authorities on a highway near their Manchester home last Saturday, hours after the car-bomb attempt at the Glasgow airport.

Haneef, 27, was arrested in Brisbane, Australia, on Monday as he allegedly tried to leave the country on a one-way ticket. The Brisbane Times reported in today's editions that Australian police questioned five other Indian doctors yesterday.

Haneef, who worked in Liverpool, in northwest England, before finding work in Australia in September, is related to two of the doctors held in Britain: Kafeel Ahmed, also known as Khalil Ahmed, the alleged driver of the Jeep Cherokee that rammed into the Glasgow airport terminal, and his brother Sabeel Ahmed, British reports said.

In London yesterday, security was tightened as the nation prepared to mark today's second anniversary of the suicide bombings that killed 52 people and wounded more than 700 in London on July 7, 2005.

Meanwhile, British authorities issued the first formal charges in the case. Bilal Abdullah, 27, an Iraqi doctor, was charged with conspiring to cause explosions. Authorities say he was in the Jeep that rammed the Glasgow terminal.

"Other individuals arrested by the police in connection with the bomb attacks remain in custody pending a charging decision," prosecutor Susan Hemming said.

Hemming said the charge would relate to the incidents last week in London and Glasgow. In London, two explosives-packed cars were parked in a nightclub district but were discovered and disarmed before they detonated.

Witnesses said Abdullah appeared calm during the attack.

"It was as if they were waiting there to get blown up," said Police Sgt. Torquil Campbell, who arrested Abdullah and Ahmed in the packed airport terminal hall. The driver remains hospitalized with severe burns.