SALT LAKE CITY — Congressional investigators are looking at the government’s quick — and legal — approvals for oil and gas drilling in an investigation called long overdue by environmental groups. Industry executives condemn it as political.

Two Government Accountability Office investigators are in Utah as part of a probe into the Bureau of Land Management’s practice of approving some drilling projects without a full environmental study of the consequences.

The practice, authorized by the 2005 Energy Act, has been used thousands of times at field offices in Price and Vernal, Utah; Farmington, N. M.; and Pinedale, Wyo., said GAO officials, citing the bureau’s own figures. Agency officials say they were just doing their job, and that they don’t set policy.

On Tuesday, the investigators visited eastern Utah’s Nine Mile Canyon, an area with thousands of ancient rock art panels that has turned into a battleground over energy development.

Three environmental groups are fighting plans by Denver-based Bill Barrett Corp. to drill more than 800 new gas wells in the area, adding to the truck traffic that can stir up dust and coat the art panels.