NIAMEY (Reuters) - At least 22 soldiers were killed in Niger on Thursday when unknown assailants attacked a camp for Malian refugees, the West African nation's Prime Minister Brigi Rafini said.

"We received information of an attack on the camp in Tassalit. For the moment we are told there are 22 dead, but that is not a total death toll," he said in comments broadcast on state-run television TeleSahel. "The death toll could increase."

(Reporting by Boureima Balima; Writing by Joe Bavier; Editing by James Dalgleish)