HOHHOT -- Preliminary investigation showed that lightning strikes caused forest fires in North China's Inner Mongolia autonomous region Saturday, according to the national forest fire prevention headquarters.

No casualties or damage of major facilities have been reported so far, it said.

A fire broke out at around 10 am Saturday in a primeval forest in the northern area of the Greater Hinggan Mountains in the region. The fire has engulfed around 30 hectares of forest in this area.

Another fire in a national nature reserve was found at around 5 pm and the fire has spread to about 200 hectares.

Nearly 2,000 forest police and fire fighters have been mobilized to battle forest fires. Eight helicopters have also been sent to the sites to put out fires.