A female suicide bomber has injured at least 11 police officers and civilians in the southern Russian region of Dagestan, police said.

Dagestan's police spokesman Vyacheslav Gasanov said the bomber blew herself up on the central square in the provincial capital, Makhachkala.

Since 2000, at least two dozen female suicide bombers, most of them from the Caucasus, have carried out terrorist attacks in Russian cities and aboard trains and planes.

All were linked to an Islamic insurgency that that spread throughout Dagestan and the predominantly Muslim Caucasus region after two separatist wars in neighboring Chechnya.

The bombers are often called "black widows" in Russia because many of them are the wives, or other relatives, of militants killed by security forces.