RABAT, Morocco — France's foreign minister says documents found in northern Mali show that the Nigerian extremist group Boko Haram was being trained there by other al-Qaida-linked groups.

Speaking at a conference about security in North Africa and the Sahara region being held in Morocco Thursday, Laurent Fabius said "documents were found that terrorists from Boko Haram were being trained in the Ifoghas mountains" in northern Mali.

Al-Qaida's North Africa branch teamed up with extremists from the desert-dwelling Tuareg people to take over northern Mali, but they were driven out by a French-backed African force early this year.

Boko Haram, which was designated a terrorist group by the United States on Wednesday, wants to impose Islamic law in northern Nigeria and is believed to be responsible for thousands of deaths.