DAKAR, Jan 9 (Reuters) - Seven U.N. peacekeepers were injured in the northern Malian town of Kidal on Friday when their vehicle was struck by an explosion near the town's airport.

The U.N. mission said four of the soldiers were lightly injured while three others suffered fractures. A witness said the troops involved were Senegalese. It was not clear if the vehicle hit a land mine or an improvised explosive device.

Peacekeepers have deployed to try to secure northern Mali but Islamists driven from the desert zone two years ago by French forces are increasingly attacking U.N. troops in ambushes and with roadside bombs. (Writing by David Lewis; Editing by Alison Williams)