WASHINGTON (AP) — A federal advisory panel is warning that "serious environmental consequences" could result from the gas drilling technique known as hydraulic fracturing if steps aren't taken to reduce its impacts.

The seven-member committee said in a report released Thursday that progress by the federal government and the oil and gas industry on 20 recommendations it issued in August has been less than it hoped. It said if actions were not taken to avoid "excessive environmental impacts," a public outcry could delay or stop the gas drilling boom.

Energy Secretary Steven Chu asked the panel in May for advice on ways to improve hydraulic fracturing's safety and environmental soundness.

It recommended reducing air pollution and eliminating diesel fuel and disclosing all other chemicals pumped underground to fracture rock and access natural gas.