Specialist police have entered a school in eastern France where a 17-year-old armed with two swords is holding a group of children hostage.

The young man had taken around 20 children hostage in the eastern city of Besancon just after the school opened on Monday morning, but released a dozen shortly after.

Around five or six are said to still be inside the school with the hostage.

The man "went into the establishment armed with two swords and declaring that he wanted something," but did did not say what exactly that was, Jean-Louis Fousseret, the city's mayor said.

"For the moment I am optimistic, he said, adding: "Of course the families are worried."

Officers have been in contact with the youth via the telephone, a police official told the AP news agency.

Luc Chatel, the country's education minister, is said to be on his way to Besancon.

French media have said the hostage-taker was known to suffer from depression, but no motive has been made clear.

Source: Agencies