A top official at Immigration and Customs Enforcement has resigned following allegations by several subordinates of lewd behavior.

ICE Chief of Staff Suzanne Barr submitted her resignation in a letter, obtained by FoxNews.com, to ICE Director John Morton. She rejected the allegations against her as "unfounded" but said she didn't want to distract from the agency's mission.

"In recent weeks, I have been the focus of unfounded allegations designed to destroy my reputation, but of greater concern however, is the threat these allegations represent to the reputation of this agency and the men and women who proudly serve their country by advancing ICE's mission," Barr wrote.

"As such, I feel it is incumbent upon me to take every step necessary to prevent further harm to the agency and to prevent this from further distracting from our critical work. Therefore, it is with great regret that I submit my resignation as Chief of Staff for Immigration and Customs Enforcement."

The resignation comes nearly three weeks after Barr went on leave over the allegations. The questions about Barr's conduct were first raised in a lawsuit filed by an ICE official against Department of Homeland Security Janet Napolitano -- the lawsuit, which alleged discrimination and retaliation, listed among the complaints that Barr cultivated a "frat-house"-style work environment.

That accusation was supplemented by two affidavits recounting incidents allegedly involving Barr in 2009.

In the affidavits, one of the ICE employees claimed that in October 2009, while in a discussion about Halloween plans, the individual witnessed Barr turn to a senior ICE employee and say: "You a sexy" (expletive deleted).

"She then looked at his crotch and asked, 'How long is it anyway?'" according to the affidavit.

"Several employees laughed nervously," the affidavit said. The names of the workers making the claims were redacted.

The other account recalled a trip to Colombia in late 2009, attended by Morton, Barr and Ray Parmer, who is ICE special agent in charge for Homeland Security Investigations in New Orleans.

The account said Parmer and Barr were "drinking heavily" at the house of the deputy chief of mission for the U.S. Embassy there. It said Parmer took the BlackBerry of another employee, Peter Vincent, and sent "lewd messages" to Barr.

The affidavit went on to say: "During this party, Suzanne Barr approached me and offered to" perform oral sex.

In her letter to Morton, Barr defended herself and said the accusations are not true.

"With time I am confident that the truth will prevail. The allegations against me are unfounded and without any merit, and I am confident that my reputation will be restored," she wrote. "I am equally confident that the agency will continue to flourish and grow. The men and women who risk their lives will continue to enjoy great success and I hope that my resignation will allow them to again focus on that which is most important."

Morris Fischer, the attorney representing the ICE official who is suing DHS, said to FoxNews.com, "We are obviously very pleased with the agency's first step in rectifying this situation by accepting Ms. Barr's resignation. Now is the time for the agency to move forward and make restitution to the individuals harmed."

Before joining ICE in January 2009, Barr worked under Napolitano while she was governor of Arizona, serving as director of legislative affairs.

Republican lawmakers have taken a keen interest in the case, questioning what it says about the culture at ICE and DHS.

"The resignation of Suzanne Barr raises the most serious questions about management practices and personnel policies at the Department of Homeland Security," House Homeland Security Committee Chairman Peter King, R-N.Y., said in a statement.

He said his committee would "intensify" its review of the case and "DHS personnel practices across the board."