William Casey, as Ronald Reagan's presidential campaign manager, allegedly cut a deal with Iran in 1980 to delay the release of U.S. hostages until after Election Day, ABC News says.

ABC said Iranian arms dealer Jamshid Hashemi supplied it with details of what he said were two sets of meetings in July and August 1980 in Madrid with Casey, who later became Reagan's CIA director, and two unidentified men.ABC-TV's "Nightline" program Thursday night broadcast Hashemi's description of the alleged meetings that supposedly took place in the midst of the Carter-Reagan presidential campaign. The network said Casey's campaign schedule was uncharacteristically blank for July 27-29 and Aug. 8-13, 1980.

White House Press Secretary Marlin Fitzwater Friday morning refused to comment directly on the ABC report, saying all the White House had to say on those allegations was in a May 9 letter to former hostage Moorhead Kennedy from President Bush, Reagan's running mate at the time of the alleged incidents.

In the letter Bush denied any knowledge of "such an insidious plot."

The network quoted a newspaper story of July 30, 1980, in which a Reagan campaign spokesman said Casey planned to return home that day "from a trip abroad." Casey died in 1987.

There have been reports for the past decade that the Reagan campaign made a deal with Iran's ruling clerics to delay until after the election the release of the 52 American hostages seized in the takeover of the U.S. Embassy in Tehran in 1979.

The reports were revived recently by Gary Sick, a member of the National Security Council staff in the Carter administration. Sick said there is substantial circumstantial evidence pointing to such a deal.

According to Hashemi, who refused to go on camera, Iran was represented in the Madrid meetings by Iranian cleric Mehdi Kharoubi and his brother, Hassan. Hashemi said he and his brother, Cyrus, who has since died, acted as interpreters.

The hostages were released within minutes of Reagan taking office on Jan. 20, 1981. The arrangements had been made by the Carter administration in negotiations using Algerian representatives as intermediaries.

ABC's investigation is being undertaken in cooperation with the Financial Times of London.