NICOSIA, Cyprus (AP) _ Iran's foreign minister says efforts to free Western hostages in Lebanon have reached a dead end, chilling hopes that they might soon be released.

The minister, Ali Akbar Velayati, said Friday that efforts were stalemated because the hostage captors had gotten nothing for captives they had released in the past, Tehran radio reported.

Velayati repeated Iran's previous conditions for gaining the release of the hostages: release the hundreds of Arab prisoners held by Israel and its proxy, the South Lebanon Army militia.

He also said relations with the United States, severed in 1979, could improve only if America frees billions of dollars of Iranian assets frozen in the United States.

But he did not link that issue to the hostages. Iran denies any involvement with the hostage-holders, saying it only has influence with them.

The radio, monitored in Nicosia, said Velayati was speaking in an interview with two U.S. television networks.

Hopes for the freedom of 13 Westerners missing in Lebanon had risen recently with reports in Lebanese newspapers that a hostage deal was imminent.

Those hopes were also raised by Iran's release last week of British businessman Roger Cooper, jailed since 1985 on charges of espionage.

Dutch Foreign Minister Hans van den Broek returned from a visit to Tehran Thursday saying Iran ''is ready and already making efforts'' to win freedom for the captives.

Six Americans and seven other Westerners are missing and believed held hostage by pro-Iranian Shiite Muslim fundamentalist groups in Lebanon. The longest-held is Terry Anderson, chief Middle East correspondent for The Associated Press, who was kidnapped March 16, 1985.

Sources in Tehran had said that a deal to free the hostages was being worked out, and that last week's visit to Tehran by Swiss Foreign Minister Rene Felber had been significant. Felber sometimes acts as an intermediary with Washington.

But when interviewers asked when the Westerners might be freed, Velayati said that those efforts had ''reached dead end.''

Referring to the release last year of two American and one British hostage, Velayati said, ''We were able to free some of these hostages.

''But currently, because the Lebanese groups who freed the hostages gained nothing from the United States, and in fact have witnessed negative reactions from it, we have reached a dead end,'' he said.

''We hope our hostages in Lebanon and Israel are freed,'' Velayati said.

''So far more than 400 Lebanese are hostages in Lebanon, and because the United States and Britain ... have great influence in Israel, they can free them,'' he added.

Iran has also linked the hostages to information about four Iranian diplomats who disappeared in Lebanon's Christian enclave during Israel's 1982 invasion of Lebanon. They were reportedly killed by Christian militamen, but no bodies were ever found.

Velayati did not mention them, nor did he speak of Sheik Abdul Karim Obeid, a Lebanese Shiite Muslim clergyman abducted from his south Lebanese village by Israeli paratroopers in July 1989.

Obeid's release was a condition raised by several of the hostage-holding groups.

Sources in Tehran earlier said Iranian officials had perceived an unprecedented seriousness in Washington to deal with the hostage issue in a ''comprehensive manner.''

Speaking on condition of anonymity, the sources said that Washington had promised to free Iranian assets, which include investments and military purchases made by the late Iranian monarch, Shah Mohammad Reza Pahlavi, before the 1979 Islamic revolution.

Washington froze the assets after the Shah was toppled by the anti-American Islamic government, and the U.S. Embassy in Tehran was stormed by Islamic militants, who held 52 Americans for 444 days.