A Scottish house had been used as a makeshift bomb factory to carry out the terror attacks in London and Scotland, British media reported Thursday.

Britain’s terrorism threat level has been lowered following the capture of eight people connected with the three failed car bombings but authorities were still investigating the possibility of a sleeper cell operating in the country.

At least two of the suspects — mostly doctors — allegedly rented a house just a few miles from the Glasgow airport where two men crashed a gas-laden Jeep Cherokee into the barriers outside the main terminal. The two men slept upstairs and used the downstairs as a makeshift bomb factory, several British news outlets reported citing unidentified sources.

Brian Harvey, a 60-year-old construction worker who lives on the street where the house is located, said he had seen a green sports utility vehicle outside the property being searched. He said the car was nicer than most found in the neighborhood.

Police were still outside of the house on Thursday morning.

Two other suspects allegedly stayed at medical staff accommodation at the Royal Alexandra Hospital in Paisley, British newspapers reported. Scotland Yard refused to confirm any of the reports.

A British investigator, meanwhile, was questioning an Indian doctor arrested in Australia.

Australian police acting on information forwarded from British counterparts arrested Muhammad Haneef, 27, on Monday in the eastern city of Brisbane as he tried to board a flight with a one-way ticket, believed to be to India via Malaysia.

Haneef worked in 2005 at a hospital in northern England where another suspect arrested in connection to the failed attacks also worked. He moved to Australia last year and is one of suspects detained over the plot in which two car bombs failed to explode in London on Friday, and two men rammed the Jeep with gas cylinders into the entrance of Glasgow International Airport Saturday.

There have been 38 racist incidents in the Glasgow area since the attack, and tensions have been running high, police said.

There have been a number of beatings, including a revenge attack on a white youth by three South Asian youths who believed he had been involved in a previous racially motivated attack. An South Asian owned shop was also set on the southside of Glasgow — an area with a heavy concentration of Muslims.

Other incidents included verbal attacks. There were no serious injuries.

Community leader Bashir Maan appealed for calm in the city and said community relations remained strong.

“We must remember these people were not from Scotland,” he said.

Six physicians are among the eight suspects — one each from Iraq, Lebanon and Jordan and two from India. Also in custody are the Jordanian’s wife, a medical assistant, and a doctor and medical student thought to be from the Middle East, possibly Saudi Arabia. None has been charged.

Prime Minister Gordon Brown said there will be increased scrutiny of foreigners recruited for their skills, including doctors coming to work for the National Health Service.

“We’ll expand the background checks that have been done where there are highly skilled migrant workers coming into this country,” Brown told the House of Commons in his first appearance at the weekly prime minister’s questions.

Several of the suspects were on a watch list compiled by the domestic intelligence agency MI5, a British government security official said, indicating their identities previously had been logged by agents. The official did not say why they were put on the watch list.

The official said Britain’s security services are watching about 1,600 people and have details logged about hundreds more.

A U.S.-based intelligence monitoring group said Wednesday that it obtained a copy of a video in which al-Qaida’s No. 2 leader urges Muslims to unite in a holy war against the West. But it did not mention the bombing attempts in Britain.

It was not possible to determine from the transcript released by the group SITE whether the video of Ayman al-Zawahri was recorded before the attacks.

The Times of London said one of the eight people in custody, Iraqi-born physician Bilal Abdulla, reportedly had links to radical Islamic groups and several others were linked to extremist radicals on Britain’s watchlist.

Abdulla was a passenger in the Jeep that smashed into Glasgow’s airport. Investigators believe the same men who parked two explosives-laden Mercedes cars in London may have also driven the blazing SUV in Glasgow, officials say.