A senior Syrian official said today that the release of French citizens seized in Beirut was just "a matter of time" following negotiations involving the kidnapers and the Syrian and Iranian governments.

The statement by Defense Minister Gen. Mustafa Tlas appeared to confirm reports here and in the Middle East of a possible breakthrough in the hostage negotiations. In an interview in Damascus with a French radio station, Tlas described the release of the French hostages as "certain" but refused to predict a precise date.

The latest reports about an imminent release of French hostages follow a significant improvement in relations between Paris and Tehran and the visit here last week by the Iranian deputy prime minister, Ali Reza Moayeri. Islamic groups who are holding a total of nine French citizens have called on France to moderate its support for Iraq in the 5 1/2-year Persian Gulf war with Iran.

Tlas, who has the reputation of being outspoken but not always accurate, did not mention the fate of four American citizens who are also being held in Lebanon. In an interview published May 18, Syrian President Hafez Assad said French President Mitterrand was the leader "most concerned" about releasing the hostages.

Assad has acknowledged that previous attempts to secure the release of the French hostages have failed at the last moment. In the interview, he said Syria did not have direct contacts with the splinter groups that were actually holding the hostages.

The Syrian defense minister said that the liberation of the French hostages had been delayed as a result of the April 15 attack on Libya by the United States and what he described as "American pressure on Syria." Some U.S. officials have accused Damascas of involvement along with Libya in recent acts of state-sponsored terrorism.

Noting that Assad had personally urged Iranian President Ali Khamenei to use his influence on behalf of the French hostages, Tlas told the Europe 1 radio station: "We are convinced and persuaded that their liberation is just a matter of time."

It was unclear from the defense minister's remarks whether he was speaking of all the French hostages or merely some of them. The hostages -- who include five journalists, two diplomats, an academic and a retired 84-year-old businessman -- are being held in several separate groups.

Tlas also indicated that the Syrian president hoped to use an eventual release of the hostages to improve his reputation among western countries as a responsible Middle East leader at a time when his government is under political pressure.

"Obviously this will demonstrate that those who can release hostages have influence in the region. I am convinced that it will be President Assad who will free the hostages," he said.

Today, Assad completed a three-day trip to Greece during which he seemed anxious to counter charges that his country was involved in terrorism. "We in Syria are willing to cooperate with the international community to combat terrorism," he said at a banquet last night. He also held unexpected talks with Jordanian Prime Minister Zeid Rifai in an apparent move to mend diplomatic fences with a centrist Arab country.

Last week's visit to France by an Iranian delegation headed by the deputy prime minister marked a resumption of high-level ties after a six-year interval. Attempts to improve relations have been complicated in the past by a financial dispute dating to the 1979 Iranian revolution and massive sales of French military equipment to Iraq.

Addressing the French Senate last night, French Foreign Minister Jean-Bernard Raimond cited "progress" in the hostage negotiations over the past week. French officials have said that the government is in touch with both Damascus and Tehran in an attempt to release the hostages.

The Associated Press reported on the latest violence in Beirut:

Gunmen shot dead two Armenians in separate actions in west Beirut, police said, while Shiite Moslem militiamen and Palestinian guerrillas battled for a 10th day on the southern edge of the Lebanese capital.

Two other Armenians were killed yesterday, police said. Authorities said they had no leads in the shootings. The three major Armenian political parties issued a joint statement denouncing "this ugly criminal wave against Armenian citizens in west Beirut."