A large mob has attacked a checkpoint in a remote part of China's northern Inner Mongolia region, state media say.

About 100 masked attackers beat staff and destroyed buildings before escaping, according to the China News Agency.

No motive has been given and police are searching for those involved.

The region has in the past seen tensions between minority ethnic Mongolians and Han Chinese.

Some 13 people were injured in the early morning raid in Ejin Banner county, the reports said.

The attackers were armed with sticks and pepper spray, using construction equipment to wreck the checkpoint and several vehicles, the China News Agency said.

The group stole money, mobile phones and other items.