BUCKHANNON, W. Va. - One or more lightning strikes likely caused an electrical current in a cable left deep inside the Sago Mine and touched off the methane blast blamed for the deaths of 12 coal miners last year, the federal Mine Safety and Health Administration said yesterday.

Lightning is one of three "root causes" the agency cites in its long-awaited investigation into the Jan. 2, 2006, explosion.

Lightning had been suspected from the start, but the report for the first time describes its likely path, saying an electrical current traveled through the earth to the 1,300-foot-long cable. Previous reports by the state and the mine's owner, International Coal Group Inc., mentioned lightning but not its route.

Electrical currents could have traveled through the earth to the underground pump cable, which functioned like an antenna, the report said.

Atmospheric alarms in the mine sounded at nearly the same instant as a documented lightning strike, at 6:26 a.m. on Jan. 2. The National Lightning Detection Network recorded two lightning strikes near the mine - one a mile south of the mine's opening, one a mile to the north.

Contributing to the blast, according to the report, methane levels inside the sealed section of the mine were not monitored, and seals used to close off that inactive section from the mine's working area were not strong enough to withstand the blast.

Relatives of some of the Sago victims questioned the report. "It's going to make a difference on paper, but it's not going to make a difference to the miners who risk their lives every day trying to support their families," said Pam Campbell, whose brother-in-law died in the mine.

The explosion trapped a team of miners deep inside the mine. By the time searchers reached them about 40 hours later, only one man had survived in the carbon monoxide gas.