Washington ? President Barack Obama on Thursday ordered a sweeping review of coal mines with poor safety records and called on federal officials to strengthen laws “so riddled with loopholes that they allow unsafe conditions to continue.”

Obama spoke after receiving a preliminary report on last week’s deadly mine explosion in West Virginia that suggests the blast may have been caused by a preventable buildup of methane gas mixing with coal dust.

The report from Labor Secretary Hilda Solis and mine safety officials cautioned that the specific cause of the blast at the Upper Big Branch mine where 29 workers died is still being determined. But it raised serious concerns about a major spike in safety violations at the mine owned by Massey Energy Co.

The report says the rate of serious violations in 2009 that required mine workers to leave while immediate repairs were made was nearly 19 times the national rate.