THE HAGUE, JUNE 15 -- Iran agreed today to pay the American oil company Amoco $600 million for facilities seized during the 1979 Islamic revolution, according to an official of the tribunal settling financial claims between the United States and Iran.

It was the first major settlement of more than $1.8 billion worth of claims by U.S. oil companies filed with the Iran-United States Claims Tribunal, which has been arbitrating such cases since 1981. The two nations severed ties after the revolution, led by Ayatollah Ruhollah Khomeini, and the detention of 66 American hostages by Iranian militants at the U.S. Embassy in Tehran.

The Hague-based tribunal was set up as part of the Algiers Accord of 1980, which paved the way for the release of the hostages. The tribunal is the only forum where American and Iranian officials have been meeting throughout their nations' decade-long confrontation.

U.S. and Iranian officials have stressed that their talks do not deal with the fate of the six U.S. hostages being held by Iranian-backed groups in Lebanon. But a smaller settlement was reached last month, shortly after two U.S. hostages were freed.

The tribunal consists of three American, three Iranian and three third-nation arbitrators, and has so far settled $3.2 billion worth of government and private claims.

Amoco's claim included $540 million for Iran's expropriation of four offshore drilling fields in the gulf. One field includes Kharg island, the shipping center for most Iranian oil.