US Secret Service received 64 complaints of misconduct
Sixty-four allegations of sexual misconduct have been made against the US Secret Service over the past five years, a Senate panel has heard.
Joseph Lieberman said the claims were "troubling", as he addressed the first congressional inquiry into the agency's Colombian prostitution scandal.
Many of the 64 complaints involved sexually suggestive emails, but one was of non-consensual intercourse, he said.
Secret Service director Mark Sullivan apologised on behalf of his agency.
At least four employees forced out over the scandal are fighting the decision, the Washington Post reports .
Eight Secret Service employees, including two supervisors, have lost their jobs, with four other agents and a dozen military personnel also implicated.
The Secret Service was in the Colombian resort city of Cartagena in April preparing the way for President Barack Obama's visit for the Summit of the Americas.
The affair hit the headlines after police intervened in a dispute over payment between one of the agents and a prostitute at a hotel.
Homeland security committee chairman Sen Lieberman and Senator Susan Collins made clear their belief that what happened in Colombia was far from a one-off.
In his opening statement, Sen Lieberman, an independent, said that if the agent had not argued with the prostitute, "the world would have never known this sordid story".
Of the 64 complaints the agency fielded in the past five years, three involved inappropriate relationships with a foreign national, but one was a complaint of non-consensual intercourse.
The Secret Service's director testified that law enforcement had investigated the non-consensual intercourse allegation, but the matter did not proceed further.
In the cases of the inappropriate relationships, Mr Sullivan said administrative action had been taken.
Sen Collins, a Republican, warned that the facts of the Cartagena scandal, including that employees used their real names to check the women into the hotel, "unfortunately suggest an issue of culture".
"Contrary to the conventional story line, this was not simply a single, organised group that went out for a night on the town together," Sen Collins said.
She also argued that even if agents did not have sensitive documents with them in the hotel, they had "willingly made themselves potential targets not only for intelligence or security services, but also for groups like the [Colombian rebels] Farc or drug cartels".
Mr Sullivan testified that there was no security breach in Cartagena and that the behaviour of those involved in the scandal did not represent the conduct of the agency at large.
"At the time the misconduct occurred, none of the individuals involved in the misconduct had received any specific protective information, sensitive security documents, firearms, radios or other security-related equipment in their hotel rooms," he said.
The director called his employees "among the most dedicated, hardest working, self-sacrificing employees within the federal government", adding that the incident had been an "aberration".
When asked about a Washington Post report that such conduct was unofficially accepted under a unwritten code, Mr Sullivan said: "The notion that this is condoned or authorised is absurd."
The agency tightened guidelines on employees travelling overseas shortly after the scandal.