MORGANTOWN, W.Va. — A 36-foot crack in the Upper Big Branch mine isn't venting methane and didn't contribute to a blast in April that killed 29 men, a federal official said Friday, disputing a company's claim that the crack could have caused the blast.

The crack has been the subject of a running dispute between the Mine Safety and Health Administration and the mine's owner, Virginia-based Massey Energy. Company officials have suggested a massive crack could have unexpectedly flooded the southern West Virginia mine with explosive methane gas.

Ruling out any possible contributing factors at this point in the investigation is "completely irresponsible," company spokesman Jeff Gillenwater said in an e-mail.

"No one investigating the tragedy at UBB should rush to judgment," he said, insisting the crack merits further investigation.

Some of the victims' relatives said Massey told them the crack was 150 feet long. MSHA coal administrator Kevin Stricklin strongly disputed that in a media briefing earlier this week but couldn't offer an exact measurement.