At least one of the alleged plotters of the London and Glasgow car bombings had visited Al-Qaeda leaders in Pakistan, a leading British daily claimed on Monday.
Without naming the person, The Daily Telegraph said "the information suggests that the leaders of the gang may have been seeking approval from Al-Qaeda before going ahead with their plan."
According to the report, on Sunday a senior doctor at Inverclyde Royal Hospital in Greenock, Scotland, said there was a delay in one of the alleged plotters taking up his post.
"There were some problems with a visa and he was about two weeks late getting here," the unnamed doctor said. "There were calls from him about the delay and he was in Pakistan at the time."
The main figures in other plots, including the July 7, 2005 suicide bombers, the fertiliser gang and "gas limo" terrorists all visited al-Qaeda leaders in Pakistan before finalising their plans, the report said.
It is likely that the car bomb plot was inspired by attacks in Iraq but needed clearance from the Pakistan cells before it was sanctioned by Al-Qaeda, the newspaper said.
The bomb-making tips could have been gleaned from Arabic websites which gave details of how to make gas cylinders explode.
Quoting sources, the newspaper said potassium chlorate from household matches formed a key ingredient of the detonators.
The jeep which was driven into Glasgow airport in flames a week ago was bought for 1,720 pounds and parked in Liverpool, the report said.
The cell suspected of planning the attacks comprised young men, mostly doctors, from India and the Middle East.
Kafeel Ahmed, 27, the Indian engineer suspected of being the bombmaker, lies critically ill in Glasgow Royal Infirmary's burns unit after being transferred from the Royal Alexandra Hospital in Paisley. New pictures have emerged of Kafeel, showing him with a beard on his Indian driving licence.
He had been living in Houston in Renfrewshire with Bilal Abdullah, 27, who was born in Aylesbury but brought up in Iraq and worked at the Royal Alexandra.
Two other junior doctors, aged 25 and 28 and living at the Royal Alexandra have also been arrested.
Abdullah is the only man so far charged with an offence and appeared in court at the weekend accused of conspiracy to cause explosions.
Kafeel Ahmed's brother, Sabeel, 26, a junior doctor living in Liverpool, remains under arrest at Paddington Green police station, London, after a judge agreed to extend the time limit to question him on Saturday.
Also being questioned is Mohammed Asha, 26, a junior doctor at the North Staffordshire Hospital, who was arrested along with his wife Marwa, 27, on the M6 motorway.
The Ahmeds' cousin, Mohammed Haneef, 27, is being questioned in Australia.