The U.S. State Department on Monday pledged a full investigation following revelations about possible cover-up of allegations of misconduct within its ranks.

"We take allegations of misconduct seriously, and we investigate thoroughly," department spokeswoman Jen Psaki said at a regular news briefing.

Several recent investigations were "influenced, manipulated or simply called off," the CBS TV network reported earlier in the day, quoting an internal department inspector general's memo.

The memo cited eight specific cases, including allegations that a State Department security official in Beirut, Lebanon "engaged in sexual assaults" on foreign nationals hired as embassy guards, and a charge that members of former Secretary of State Hillary Clinton's security detail "engaged prostitutes while on official trips in foreign countries," a problem the report described as " endemic."

The document also offered details about an underground drug ring that operated near the U.S. embassy in Baghdad and supplied State Department security contractors with drugs.

In one case, an American ambassador, who held a "sensitive" diplomatic post, was suspected of "patronizing prostitutes in a public park," but agents were told to stop investigating his case, CBS said.

"All cases mentioned in the CBS report were thoroughly investigated or under investigation, and the department continues to take action," Psaki said. "I can say broadly that the notion that we would not vigorously pursue criminal misconduct in a case, in any case, is preposterous."

"And we've put individuals behind bars for criminal behavior," she added. "There is record of that. Ambassadors would be no exception."