A police exercise involving motorcycle outriders and a mock target vehicle with blacked out windows was undertaken last night between Greenock and Prestwick airport. It is understood the exercise was carried out as a rehearsal to prepare for the flight of Abdelbaset Ali Mohmad Al Megrahi to Libya, understood to be taking place imminently.

The convoy were sighted simulating the necessary road and junction closures along the M77 from Glasgow. 

The transfer is expected to be announced during Thursday, with Megrahi's repatriation to Libya being executed almost simultaneously or immediately afterwards.

Prestwick Airport was the landing point for the G8 leaders during 2005, and was also the CIA's airport of choice for the rendition of suspects en route to be tortured.

No one from Strathclyde Police was available to comment.