senior Palestinian leader was reported today to have warned of the possibility of new terrorist attacks this summer by a radical, breakaway Palestinian faction against French, American and Italian targets.

The reports, which were carried in most French newspapers, said that the warning had been delivered at a secret meeting in Paris in December between senior French officials and Salah Khalaf, also known as Abu Iyad, the top aide to Palestinian leader Yasser Arafat.

Abu Iyad was said to have told the French authorities that the guerrilla operation was being planned by a breakaway faction from the Palestine Liberation Organization led by Abu Nidal, Arafat's most implacable foe in the Arab world.

Abu Nidal's group claimed responsibility for the killing Sunday of Issam Sartawi, a leading moderate PLO figure who was gunned down in Portugal at a congress of the Socialist International.

Abu Nidal, who has operated out of Iraq and Syria in recent years, was expelled from the PLO by Arafat in 1972 and was blamed by the PLO in the late 1970s for the assassination of its representatives in Paris and London as well as attacks elsewhere.

The PLO has declared a death sentence against Abu Nidal, and he, in turn, has called for the death of Arafat and Abu Iyad.

French commentators suggested that the December talks indicated that both Arafat and the French government have a joint interest in halting a wave of terrorism by radical Palestinian factions.

Last year France was one of the prime targets of international terrorism. At least 20 people, including the U.S. military attache, were killed in bomb attacks and assassinations. The number and gravity of such incidents has dropped sharply since October.

French officials refused to comment on the reports.

The revelations of the talks put the French authorities in a delicate position since they have been seeking to use diplomatic pressure to prevent a U.N. Conference on Palestine from taking place in Paris this summer. Officials fear that the conference, which will enjoy extraterritorial protection since it is to be held at the Paris headquarters of the U.N. Educational, Scientific and Cultural Organization, could provoke disturbances between the Jewish and Arab communities here.