BEIRUT, JULY 23 -- The Iranian-backed Islamic Jihad, exerting new pressure against France in a worsening diplomatic crisis over Persian Gulf policy, threatened today that no French hostage would "come out alive" unless the group's demands were met.

The statement, accompanied by a photograph of French journalist Jean Paul Kauffmann, kidnaped here in May 1985, disclaimed a previous threat to kill two French hostages made by telephone to news agencies last week.

"We reassert once again that our demands are clear and France knows them well," the statement, delivered to a news agency, said. "None of the hostages will come out alive if our demands are not met in full."

It was not clear whether the group was referring only to the French hostages or to all western hostages it holds.

Islamic Jihad has repeatedly asked for a cessation of all French military aid to Iraq and the release of 17 Shiite Moslems convicted and imprisoned in Kuwait for terrorist bombings against Kuwaiti, French and U.S. targets there in 1983.

Release of the Islamic Jihad statement came after an announcement by France that it would provide protection to French shipping in the gulf. Tensions between Paris and Tehran grew last week when France broke diplomatic relations in a dispute over whether it should be able to question an Iranian Embassy official in Paris in connection with terrorist bombings there.

No specific mention was made in today's Islamic Jihad statement about two American captives, journalist Terry Anderson and agronomist Thomas Sutherland. Anderson, the bureau chief of The Associated Press in Beirut, and Sutherland, the dean of the School of Agricultural Engineering at the American University of Beirut, were both kidnaped in 1985 and they are believed to be held by the group.

Last Friday, hours after France broke diplomatic ties with Iran, an anonymous caller told a western news agency that Islamic Jihad would kill two French hostages. Islamic Jihad today criticized western news organizations for publishing that unverified threat, which it said was not authentic.

The statement also accused western news organizations of exploiting the French-Iranian conflict and ridiculed warnings by France that it would not stand by quietly if its hostages were harmed. Islamic Jihad told France not to forget the fate of Michel Seurat, a French researcher whom the group says it killed in March 1986 after he was kidnaped.

Islamic Jihad recalled that it had not hesitated in announcing Seurat's death. It also referred to other blows directed at France such as the suicide truck bomb attack against headquarters of French paratroopers in Beirut on Oct. 23, 1983.