A safety official says he's subpoenaed some 100 witnesses to the West Virginia mine explosion after employees of owner Massey Energy started skipping voluntary interviews.

Virginia-based Massey has asked a Raleigh County Circuit Court judge to quash subpoenas issued by the state Office of Miners' Health Safety and Training. Massey contends the federal Mine Safety and Health Administration is using the state to expand its subpoena power beyond formal public hearings.

West Virginia mine safety chief Ron Wooten called Massey's argument misleading during an interview Monday.

The state and MSHA are conducting a joint civil investigation of the blast at Upper Big Branch, which killed 29 miners April 5. The explosion also is the subject of a federal criminal investigation.