Britain secretly supplied Israel with plutonium during Harold Wilson's Government, despite a warning from British intelligence that the material could help Israel get the atom bomb, concludes a Newsnight investigation.
The investigation - broadcast tonight (Thursday 9 March 2006) on BBC TWO at 10.30pm - used material obtained under the Freedom of Information act.
And top secret documents, obtained by Newsnight under freedom of information, also show how Britain made hundreds of shipments to Israel of restricted materials which could have helped their nuclear weapons programme.
The Wilson Government also sold them lithium compounds which would have enabled Israel to make weapons ten times as powerful as the bomb that devastated Hiroshima.
Yet Tony Benn - who was Minister of Technology and in charge of exporting nuclear material - has told Newsnight that Government officials and civil servants in his own department kept all these deals totally secret from him, and from his predecessor Frank Cousins.
Benn says he always suspected civil servants were doing deals behind his back but he never thought they would sell plutonium to Israel.
He tells Newsnight: "I'm not only surprised I'm shocked."
He later adds: "It never occurred to me they would authorise something so totally against the policy of the Government."
Benn thinks the Prime Minister, Harold Wilson, may not even have known that the UK was helping Israel get the bomb.
In 1966 Israel asked Britain to supply ten mg of plutonium.
Although this was a small amount and Israel would have required almost five kilos of plutonium to build an atom bomb, British officials were warned this had "significant military value" and could enable Israel to carry out vital experimental work to speed up the development of nuclear weapons.
Documents obtained by Newsnight show 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 it was forced through by a Jewish civil servant in Tony Benn's Ministry of Technology, Michael Israel Michaels.
Peter Kelly, who was British intelligence's top expert on the Israeli nuclear weapons programme, knew Michaels.
He told Newsnight he believed Michaels knew Israel was trying to build the bomb but had dual loyalties - to both Britain and Israel.
On seeing the evidence gathered by Newsnight Tony Benn says: "Michaels lied to me, I learned by bitter experience that the nuclear industry lied to me again and again."
Last year Newsnight revealed how in the late Fifties Harold MacMillan's Government had provided Israel with 20 tonnes of heavy water which they needed to start up their Dimona reactor.
The Foreign Office responded to the programme by telling the International Atomic Energy Agency that the UK had only sold the heavy water to Norway but papers obtained by Newsnight show Britain shipped it directly to Israel.
Newsnight has now learnt that Foreign Secretary Jack Straw has admitted to Liberal Democrat leader Sir Menzies Campbell that Britain did know the heavy water was going to Israel and that in 1961 Harold Macmillan even made a failed attempt to get it back.
Notes to Editors
Any use of this material must be credited to BBC Newsnight.