Experts on Islamic militant groups are skeptical about a Web posting demanding $5 million in ransom for two French journalists held hostage in Iraq, France's prime minister said Monday.

Christian Chesnot (search) and Georges Malbrunot (search) disappeared Aug. 20 on a trip to the southern Iraqi city of Najaf. Intense negotiations by French diplomats and overwhelming support from the Arab world and France's own large Muslim community raised hopes last week for the journalists' imminent release.

"We always treat such information seriously," Jean-Pierre Raffarin told RTL radio. But the new message "has provoked a lot of skepticism from experts."

The militants claiming to hold the men were demanding that France revoke a law banning Islamic head scarves (search) from state schools. The law went into effect as planned last week, and France has refused to back down.

The new demand for ransom within 48 hours — posted on an electronic bulletin board open to anyone — made no mention of the head scarf law.

Written in unsophisticated Arabic, it set several conditions, including that France accept a truce purportedly offered by Usama bin Laden to European countries if they leave Iraq, Afghanistan and other Muslim countries. But the deadline for that offer expired in July.

The message also demanded that France pledge no military or commercial involvement in Iraq. France has opposed the war in Iraq and has refused to send troops.

The message was signed "the Islamic Army of Iraq," the name of the group that has claimed responsibility for the kidnappings.

French government ministers say they are hopeful about the journalists' fate but do not want to jeopardize their release by talking about it too much.

"We have serious indications that allow us to believe they are in good health and that a liberation is possible," Defense Minister Michele Alliot-Marie told LCI television, adding: "The less we say about it, the better it is for them."