MORGANTOWN, W.Va. (AP) — The Mine Safety and Health Administration wants a judge to dismiss a lawsuit over how it's interviewing witnesses in a West Virginia coal mine explosion that killed 29 men.

MSHA argues the U.S. District Court in Charleston lacks jurisdiction in the case raised by the United Mine Workers of America and the families of two dead miners.

The UMW and relatives of William Griffith and Ronald Maynor want to observe private interviews. MSHA director Joe Main says they have no legal foundation for that demand.

MSHA argues a combination of private interviews and public meetings will protect the integrity of the investigation and the confidentiality of witnesses.

The cause of the April 5 blast at Massey Energy's Upper Big Branch mine remains under investigation.