France last year became the first country to outlaw the use of hydraulic fracturing, or "fracking," to tap into shale gas reserves following a popular outcry over its feared environmental consequences.
Numerous protests erupted when it was discovered the government of President Nicolas Sarkozy had issued hydraulic fracturing permits in the south of France to energy giant Total and others.
While outlawing fracking -- a process in which dense rock is broken apart by water and chemicals under high pressure to release trapped natural gas -- the French ban doesn't rule out the extraction of shale gas.
The country's current president, the Socialist Party's Francois Hollande, campaigned in favor of retaining the ban before his May election while Ayrault said last year the ban didn't go far enough and could leave room for energy companies to maneuver around it.
But in comments made during an interview last week with French broadcaster BFM-TV, Ayrault said the question isn't settled and left the door open to future shale gas extraction if a more environmentally acceptable way to do it could be found, Radio France International reported.
"For the moment all permits for the hydraulic fracture system, which has devastating effects, are forbidden," he said, but added, "different solutions might exist ... which may not pollute or harmful to the environment or the quality of the landscape."
The prime minister also said he would be willing to discuss "technical solutions," if they exist, as part of a Sept. 14 national conference on environmental policy.
The comments revealed what appeared to be a split within the government on the future of shale gas in France, which is believed to hold the most reserves of any European country besides Poland.
Environment Minister Delphine Batho asserted fracking remains the only known way to extract shale gas, telling the broadcaster this month she remains unalterably opposed to it.
"The government maintains its position on the prohibition of the exploitation of shale gas," she said, adding that "nowhere in the world has it been shown that this operation could be done without considerable damage to the environment and with significant risks to health."
Ayrault's remarks were met by alarm from French environmentalists who thought the election of the Socialists had solidified the country's direction against shale gas.
Pascal Durand, leader of the Europe Ecology-Greens Party, said the idea of an environmentally safer form of shale gas extraction is a "false debate" and is merely case of "misinformation from a number of oil companies trying to pretend we could go on with the exploration of shale gas without (using) hydraulic fracturing."
Nathalie Kosciusko-Morizet, the former environment minister under Sarkozy, said Ayrault's comments showed the "duplicity" of the government on shale gas.
This summer, Total and other French energy companies went on the offensive to publicize the benefits of shale gas production, inviting the French media to visit the facilities of its U.S. shale gas partner Chesapeake Energy, the Paris daily Le Point reported.
Jean-Louis Schilansky, president of the French Union of Petroleum Industries, said the goal was to "prove that the environmental impacts (of shale gas production) have been reduced considerably" in North America since an industry boom began there.
The boom has resulted in lower U.S. natural gas prices, a price shift that could benefit France, he said.