A lawsuit filed by the families of six men killed in a Utah mine cave-in claims that the collapse occurred because the mine's owners were harvesting coal unsafely.

The suit filed Wednesday in Salt Lake City says Murray Energy Corp. performed risky retreat mining last summer. It seeks unspecified damages.

Six miners were killed the August cave-in in central Utah. Their bodies have not been recovered. Three men trying to reach them died 10 days after the collapse in another cave-in.

The lawsuit names Murray Energy and others affiliated with the mine, including the Intermountain Power Agency and the Los Angeles Department of Water and Power.

Murray Energy chief Bob Murray has insisted that the collapse was caused by an earthquake.

Copyright 2008 Associated Press