MOSCOW, June 11 (RIA Novosti) - Militants set off a roadside bomb and opened fire on police officers in the south Russian republic of Kabardino-Balkaria in the early hours of Thursday, injuring one officer, a police source said.

The blast went off at 2:00 a.m. local time in the town of Tyrnyauz in the Elbrus District of the North Caucasus republic as a police car was passing. The militants then opened fire with automatic weapons.

"The police returned fire. The site will be examined in the daylight hours," the source said.

The police officer is being treated in hospital.

Militant attacks have continued in the North Caucasus since the official lifting in April of the Kremlin's decade-long anti-terrorist campaign in Chechnya. Violence often spills over into nearby republics, in particular Ingushetia and Daghestan, and occasionally Kabardino-Balkaria.