NICE (AFP) - Police in southern France on Wednesday (Oct 23) detained a man who had broken into a museum overnight and threatened to turn it into "hell", before admitting him to a psychiatric hospital, authorities said.

The man, who had provoked a four-hour standoff with police, was "mentally disturbed", regional prosecutor Patrice Camberou said.

He was "a very mentally disturbed person, he was totally delusional, it was impossible to question him," said Camberou.

The museum, a historic monument, includes a medieval stone church and a vast collection of amphoras and other items from the region's Roman history.

"Some amphoras dating from the Roman period have been destroyed," Saint-Raphael's mayor, Frederic Masquelier, said at a press conference.

The man was about 18 years old but gave officers several identities, including that of the fictional "Aladdin".

The man was seized "without resistance and without violence" in the gardens of the archeology museum in the Mediterranean town of Saint-Raphael shortly after 11am (5pm Singapore time), the government's top regional official Eric de Wispelaere said.

Officers from the elite RAID crisis intervention unit as well as a bomb disposal squad surrounded the site, where several messages in Arabic, including "The museum is going to become a hell," had been scrawled on the walls, according to police sources.

De Wispelaere said the man had acted alone and no explosives were found.

The standoff led officials to lock down a large part of the historic centre of the resort town of some 35,000 people, tucked between Cannes and Saint-Tropez.

"There are barricades everywhere, the street is completely blocked off," Sebastian Belkacem, who owns the Duplex restaurant opposite the museum, told AFP by telephone.