PARIS (AP) _ Two Iranians now suspected of assassinating ex-Iranian Prime Minister Shahpour Bakhtiar were briefly detained at one point by French and Swiss police but released because the slaying had not been discovered yet, police sources said today.

The two were still in France as of Sunday and may still be in the country, French police sources said.

Mohammed Azadi, 31, and Ali Rad Vakili, 32, spent at least three nights in different hotels in southern France after being turned away from Switzerland on Wednesday because their Swiss visas were forged, according to the sources.

The two men, believed to be members of a hit squad sent to France to assassinate Bakhtiar, tried to enter Switzerland on Wednesday, using Turkish passports bearing the names Ali Kaya and Musa Kocer, the sources said.

French police and Swiss Justice Department officials said they were detained and turned over to French police, who released them a short time later because they had valid French visas, according to French police sources.

The next day Bakhtiar, 76, was found dead at his home in a western Paris suburb. His throat had been cut. Coroners said he had been dead since Tuesday night.

Bakhtiar's chief aide, Fouroush Katibeh, was also stabbed to death at the house around the time three Iranian men, including Azadi and Vakili, visited Bakhtiar.

The third man, Farqoum Boyer Ahmadi, a former Bakhtiar employee whose car was found in central Paris on Thursday with traces of blood in it, has disappeared.

Ahmadi had access to Bakhtiar without prior appointment, and police believe he was either an accomplice in the slaying or was coerced into helping the killers get into the house.

The night of the killings, torn articles of clothing, some bloodied, and shreds of Iranian passports were found in the Bois de Boulogne, a sprawling woods just outside Paris, police sources said.

A prostitute discovered the items and notified police after hearing about Bakhtiar's death on the news, the sources said, adding that police believe at least Azadi and Vakili went to the woods to get rid of their clothes and passports.

After police released photographs of the three suspects, a taxi driver reported that he took Azadi and Vakili to the town of Sallanches in southern France on Wednesday evening, according to the Interior Ministry.

They were also seen Friday near a train station in Valence, southern France, where they were believed to be trying to escape to Italy, and again on Sunday in Valence, the ministry said Tuesday.

Iranian exiles - including former President Abulhassan Bani-Sadr and Reza Pahlavi, son of the former Shah of Iran - have blamed the killings on the Tehran government.

The People's Mujahedeen, an Iranian opposition group, claimed Azadi and Vakili belong to an assassination wing of Iran's Islamic Revolutionary Guards.

Iran has officially denied involvement in Bakhtiar's slaying and blamed it on rivalry between opposition groups, or as a plot to undermine Tehran's improving relations with the West.

Bakhtiar was the last prime minister for the Shah of Iran before the Islamic revolution toppled the Shah and brought Ayatollah Ruhollah Khomeini to power in 1979.

Bakhtiar survived an Iranian-ordered attempt on his life in 1980 that left a neighbor and French police officer dead.