Chinese police have arrested nine people suspected of trafficking mentally disabled people from Leibo County in southwest China' Sichuan Province to other areas and then murdering them in coal mines to blackmail the mine owners, police said Wednesday.

The nine have been arrested in Leibo County in connection with the murders in nine provinces including Hebei, Fujian, Liaoning and Sichuan, said Ye Jianhua, head of the Leibo county's Public Security Bureau.

This was the first time the police revealed the cases.

One of the suspects surnamed Feng allegedly colluded with another two to batter Zhang, a mentally disabled person, to death with a stone in an iron mine in eastern Fujian Province on April 28.

By making the murder look like an accident, Feng asked for compensation from mine owners saying he was the victim's "relative", police said.

Feng was arrested on May 13.

Leibo police did not provide details of other cases as they were out of their jurisdiction.

"Police in the nine provinces were investigating the cases," Ye said. Leibo police would cooperate with the police in the other provinces to find out more about the crimes, he said.

In a separate case, a mentally disabled miner called Huang Suoge died in a coal mine on November 23, two days after he began working in the Chengui Mining Group in Daye City, central China's Hubei Province.