WASHINGTON (AFP) - French Foreign Minister Laurent Fabius Tuesday denounced what he called the "mass rape" of Nigerian schoolgirls kidnapped by the Islamic militant Boko Haram group.

"Sometimes in France we talk about 'forced marriage,'" the French diplomat told a press conference during a visit to Washington.

s"But that term is totally inadequate. It's really a mass rape of young girls," he said, when asked about more than 200 schoolgirls snatched from their boarding school in mid-April.

These girls "have been the kidnapped and then enslaved, and it's a mass rape that must be prosecuted and punished as such."

France is hosting a summit on Saturday focusing on the threat posed by Boko Haram and has invited leaders from at least five African countries, including Nigeria, Chad, Cameroon, Niger and Benin.

British and American delegations have also been asked to take part, but Washington has not yet decided who will lead the US team.