An Interior Department investigation describing a "culture of substance abuse and promiscuity" by workers at the agency that issues offshore drilling leases and collects royalties hit lawmakers Wednesday just as they prepared for votes next week on expanding offshore drilling. . . .

The two-year, $5.3 million investigation by Interior's inspector general found workers at the Minerals Management Service's royalty collection office in Denver partying, having sex, using drugs and accepting gifts and ski trips and golf outings from energy company representatives with whom they did government business.

The investigations exposed "a culture of ethical failure" and an agency rife with conflicts of interest, Inspector General Earl E. Devaney said.

"Employees frequently consumed alcohol at industry functions, had used cocaine and marijuana, and had sexual relationships with oil and natural gas company representatives" who referred to some of the government workers as the "MMS Chicks. . . ."

But the impact in Congress, where lawmakers are debating an expansion of the offshore oil and gas leasing program by allowing drilling in areas long off limits, was immediate.

"This is why we must not allow Big Oil's agenda to be jammed through Congress," said Sen. Bill Nelson, D-Fla., who strongly opposes any expansion of offshore drilling, especially closer to Florida. He said the report "shows the oil industry holds shocking sway over the administration and even key federal employees."

"This IG report has it all — sex, drugs and the Bush administration officials once again in cahoots with Big Oil," said Sen. Charles Schumer, D-N.Y., whose Joint Economic Committee released a report last year claiming the Minerals Management Service has failed to collect millions of dollars in oil royalties. . . .