Eight people arrested in connection with three failed car bombings in London and Glasgow all have links to Britain's National Health Service, and seven of the suspects are doctors or medical students.

With the arrest late Monday of Dr. Mohammed Haneef, a 27-year-old Indian physician at Australia's Brisbane airport, police believe all the main suspects are in custody.

But Great Britain remains on high alert since Friday's discovery of two Mercedes sedans filled with gasoline and nails in central London and the attempt to crash a burning sport utility vehicle filled with gas canisters into the main terminal building at Glasgow airport.

Hours later, police carried out a controlled explosion on a car near a mosque in Glasgow.

And thousands of travellers were evacuated from London's Heathrow airport, and left to stand in the rain after an abandoned bag was discovered.

While none of the suspects have been charged, details of connections between them began to emerge Tuesday:

• Dr. Bilal Talal Abdul Samad Abdulla, 27, the passenger in the Jeep that crashed into Glasgow Airport terminal Saturday, was medically trained in Iraq. He worked at Scotland's Royal Alexandra Hospital as a diabetes specialist alongside Dr. Khalid Ahmed, reportedly the Jeep driver. The driver remains in critical condition at Royal Alexandra Hospital for burns suffered in the attack.
• Two men, aged 25 and 28, were also arrested in residences at that hospital on Sunday. Staff identified them as a junior doctor and a medical student.
• Dr. Mohammed Asha, a Palestinian from Jordan who worked at three British hospitals, was arrested with his wife Marwa, a lab technician, on a highway Saturday night.
• Haneef, who was arrested in Brisbane while trying to board a flight to India with a one-way ticket, once worked at a hospital in northern England. It is the same hospital that employed a 26-year-old man who was arrested in Liverpool Monday.

Australians acted on British tip: PM

Mark Shone, a spokesman for Liverpool's Halton Hospital, said Haneef worked at the hospital in 2005 as a temporary doctor, coming in when needed.

Australian Prime Minister John Howard said the man was arrested after Australian authorities acted on information provided by British police.

"The first person taken into custody is an Indian national who came to Australia sponsored by the Queensland [state] Health Department," Howard told reporters.

Howard also said that a second doctor was being interviewed in relation to information given to counterterrorism authorities by the first.

British terrorism expert Sally Leivesley said it's not surprising that the suspects are doctors, considering that the top tier of al-Qaeda has always included people with doctorates and medical professionals.

"The international terrorism scene is actually dominated by people far more highly educated than the average criminal. So the medical profession is not an unexpected inclusion," she said, adding that Ayman al-Zawahri, al-Qaeda's second in command, is a doctor.

She said terrorist organizations are recruiting highly intellectual students looking for a career. Medical students who join are able to compartmentalize keeping people alive when they are ill and the decision to kill people for what they see as a benefit to society, she said.

British police have put on a show of force in recent days. Here, officers patrol Waterloo train station in central London on Monday. (Lefteris Pitarakis/Associated Press)

British authorities have reportedly asked Pakistan and several other nations to check possible links with the suspects, according to a British security official.

Officers across Britain also used heightened stop-and-search powers and armed response vehicles to hunt for anyone else who might have been involved in the plot, and police put on a show of force to bolster security at airports and train stations and on city streets.

With files from the Associated Press