All the official versions say it didn't happen. However...
On Jan. 11, 1993, Russia's Supreme Soviet sent a secret cable to the U.S. Congress. The cable claimed that Russian national security files held evidence that two U.S. Presidents and two CIA directors had committed an act of treachery with Iran's radical Islamic government in 1980.
To the shock of the task force, the six-page Russian report stated, as fact, that Casey, George Bush and other Republicans had met secretly with Iranian officials in Europe during the 1980 presidential campaign. The Russians depicted the hostage negotiations that year as a two-way competition between the Carter White House and the Reagan campaign to outbid one another for Iran's cooperation on the hostages. The Russians asserted that the Reagan team had disrupted Carter's hostage negotiations after all, the exact opposite of the task force conclusion.
"After the victory of R. Reagan in the election, in early 1981, a secret agreement was reached in London in accord with which Iran released the American hostages, and the U.S. continued to supply arms, spares and military supplies for the Iranian army," the report continued. The deliveries were carried out by Israel, often through private arms dealers, the Russians said. Spares for F-14 fighters and other military equipment went to Iran from Israel in March-April 1981 and the arms pipeline kept flowing into the mid-1980s.
Instead, the Russians considered their report "a bomb" and "couldn't believe it was ignored," the official said. Not only did the House task force keep the extraordinary Russian report secret, it ended up in a cardboard box among hundreds of documents, some unclassified and others "secret." The document boxes were piled, ingloriously, on the floor of a former Ladies' Room which had been converted into storage space, deep inside a parking garage of the Rayburn House Office Building.
http://www.consortiumnews.com/archive/xfile1.html