Two lawmakers have accused the British government of a cover-up for refusing to admit that Britain helped launch Israel's nuclear program in 1959 by secretly selling the Jewish state a batch of heavy water - a key ingredient in producing weapons-grade materials. The British Broadcasting Corp. first reported the allegations - contained in previously classified documents - in August, but Foreign Office minister Kim Howells swiftly denied the claims to the International Atomic Energy Agency. Howells' account "simply flies in the face of the known facts, now that we have access to previously classified documents," lawmaker Menzies Campbell, foreign affairs spokesman from the small centrist Liberal Democrat party, told the BBC's Newsnight program late Friday. Jeremy Corbyn, a lawmaker from the governing Labor Party who wants a committee of lawmakers to investigate, told the program that Howell's statement is "simply untrue." "Right back to the late 1950s we were a party to the transfer of nuclear technology to Israel," he said. "We were party to the development of a nuclear facility in Israel that could and has been used for the manufacture of nuclear weapons." According to previously classified papers, the 20 tons of heavy water were part of a consignment that Britain bought from Norway but later decided was surplus to requirements. The documents show how officials presented the transaction as a straight sale from Norway to Israel. The documents reveal, however, that the heavy water was transported from a British port in Israeli ships in two shipments, half in June 1959 and half a year later. There was no immediate comment from the British Foreign Office. Heavy water is used both as a reactor coolant and as a moderator in the process of turning natural uranium into weapons-grade plutonium.