Documents purporting to show extensive links between MI6 and the British media during the Cold War have been authenticated, a BBC documentary is to claim.

The documents, which were passed to a state-controlled newspaper in the Soviet Union and published towards the end of the 1960s, listed Fleet Street publications and the journalist or editor that MI6 had as its contact.

Izvestia, the Soviet newspaper, claimed in 1968 that they were authentic MI6 memos, but this was ridiculed by the organisations and journalists concerned. The Radio 4 Document programme, to be broadcast by the BBC tonight, concludes that the memos are MI6 material. Stephen Dorril, author of a history of MI6, said the documents were probably passed to the Soviet Union by George Blake,