GLASGOW, Scotland – The fast-moving investigation into failed car bombings in Glasgow and London has swept up at least six physicians and a medical student, officials said Tuesday, including a doctor seized at an Australian airport with a one-way ticket.

Many of the men had roots outside Britain – with ties to Iraq, Lebanon, Jordan and India – and worked together at hospitals in Scotland or England, officials said.

None of the plotters arrested so far is named on U.S. terror watch lists that identify potential suspects, according to a senior American counterterror official who spoke on condition of anonymity because of the sensitivity of the issue.

Staff at Glasgow’s Royal Alexandra Hospital said Tuesday the suspect badly burned in the failed attack on Glasgow airport was Khalid Ahmed, a Lebanese doctor who both worked there – as did the Iraqi arrested with him – and was being treated there under police guard.

One of the doctors from India, 27-year-old Muhammad Haneef, was arrested late Monday at the international airport in the Australian city of Brisbane, the Australian attorney general said.

Haneef, who was being held under counterterrorism laws, worked in 2005 at Halton Hospital in England, hospital spokesman Mark Shone said. A 26-year-old man arrested Saturday in Liverpool also practiced there, Shone said.

“The doctor was regarded by the hospital as, in many senses, a model citizen – excellent references and so on,” said Queensland Premier Peter Beattie.

Police in Glasgow said two more men – aged 25 and 28 – were arrested Sunday in residences at Glasgow’s Royal Alexandra Hospital, where staff identified them as a junior doctor and a medical student.

Amid increased security at British airports, train stations and on city streets, two men attempting to buy gas canisters at an industrial estate were arrested in Blackburn, northern England, under anti-terrorism laws. Police said it was too early to determine if the men were linked to the London and Glasgow attacks.

Authorities said police searched at least 19 locations at a time of already high vigilance before the anniversary of the suicide bombings in London that killed 52 people on July 7, 2005.

In the latest attacks, two car bombs failed to explode in central London on Friday, and two men rammed a Jeep Cherokee loaded with gas cylinders into the entrance of Glasgow International Airport and then set it on fire Saturday.

The British government security official said investigators were working on one theory that the same people may have driven the explosives-laden cars into London and the blazing SUV in Glasgow.

Bomb experts carried out a second controlled explosion on a car at the Royal Alexandra Hospital hospital Monday, after a similar blast Sunday. Police said the car was linked to the investigation, but no explosives were found.

Authorities identified Bilal Abdulla, an Iraqi doctor who worked at the Glasgow hospital, as the other man arrested at the airport.

A man arrested late Saturday on a highway in central England was also a physician, Mohammed Jamil Abdelqader Asha, police said. A Jordanian official said Asha was of Palestinian descent and carried a Jordanian passport.

Azmi Mahafzah, Asha’s instructor at the University of Jordan medical school, said he knew Asha during his studies and training from 1998 to 2004.

“I didn’t even have the impression that he was religious,” he told The Associated Press. “He is not a fanatic type of person.”

The family of Asha’s wife, Marwa, who British authorities said was also arrested, denied she had links to terrorism.

“Marwa is a very educated person and she read many British novels to know England better, a country she liked so much,” her father, Yunis Da’na, told The Associated Press in Jordan.

Police were also investigating an attack on an Asian news agent early Tuesday in Glasgow, in which a car was rammed into the shop and caught fire or set ablaze, and the torching of a real estate office next to a mosque near Edinburgh on Monday.

Officers have yet to establish if either attack was racially motivated, but Osama Saeed, the Muslim Association of Britain’s Scottish spokesman, said tension was increasing.

___

Associated Press Writers Rob Harris in Runcorn, England, David Stringer in London, Lara Jakes Jordan in Washington, and Shafika Mattar and Dale Gavlak in Amman, Jordan, contributed to this report.