A failed car bomb attack on Glasgow airport was unplanned and implemented out of "sheer desperation" as police closed in after twin bomb bids in London failed, a senior security source said on Thursday.
The two men implicated in last Saturday's incident in Scotland were unprepared "to the point of buying a lot of components just hours before they used them," said the source who spoke to AFP on condiion of anonymity.
"That's why it was such a cock-up," he added.
"They thought that their days were numbered because they thought that the security services were on to them and would recognise them from CCTV and therefore they went out of sheer desperation," he added.
Police linked all three failed bomb bids on the basis of evidence gleaned from two Mercedes cars packed with improvised explosives, which remained completely intact because they failed to detonate on June 29.
They also used closed-circuit television footage from the area and other parts of Britain, which the source said helped link the suspects in the case.
The day after the London attacks, two men -- identified by British media as Iraqi doctor Bilal Abdulla and Khalid Ahmed -- rammed a Jeep Cherokee into the doorway of the main terminal building at Glasgow airport.
The vehicle burst into flames on impact, set part of the building on fire, and left Ahmed struggling for his life with severe burns. Nobody else was seriously hurt.
The security source said the improvised explosives and components used in the three attacks were gathered at an address near Glasgow, but did not give the precise location.