The documents also show how Britain made hundreds of shipments to Israel of material which could have helped in its nuclear weapons programme, including compounds of uranium, lithium, beryllium and tritium, as well as heavy water.

Israel asked Britain in 1966 to supply 10mg of plutonium. Israel would have required almost 5kg of plutonium to build an atomic bomb, but British defence intelligence officials warned that 10mg had "significant military value" and could enable the Jewish state to carry out important experimental work to speed up its nuclear weapons programme.

Documents show that the decision to sell plutonium to Israel in 1966 was blocked by officials in both the Ministry of Defence and the Foreign Office, who said: "It is HMG's policy not to do anything which would assist Israel in the production of nuclear weapons." But the deal was forced through by a Jewish civil servant, Michael Michaels, in Tony Benn's Ministry of Technology, which was responsible for trade in nuclear material, according to Newsnight.

Peter Kelly, who was British defence intelligence's expert on the Israeli nuclear weapons programme, knew Mr Michaels. He told Newsnight he believed Mr Michaels knew that Israel was trying to build an atomic bomb, but that he had dual loyalties to Britain and Israel.

Mr Benn told the programme that civil servants in his department kept the deals secret from him and his predecessor, Frank Cousins.

He had always suspected that civil servants were doing deals behind his back, but he never thought they would sell plutonium to Israel. He told Newsnight: "I'm not only surprised, I'm shocked. It never occurred to me they would authorise something so totally against the policy of the government.

"Michaels lied to me, I learned by bitter experience that the nuclear industry lied to me again and again." He thought Wilson may not have known that Britain was helping Israel to get the bomb.

Last year Newsnight showed that in the late 1950s Harold Macmillan's Conservative government provided Israel with 20 tonnes of heavy water to start up its Dimona reactor. Newsnight said it learned that Jack Straw had admitted to the Liberal Democrat leader, Sir Menzies Campbell, that Britain knew the heavy water was destined for Israel, and that in 1961, Macmillan even made a failed attempt to get it back.