By Susan Cornwell and Tabassum Zakaria
WASHINGTON (Reuters) - Twenty or 21 women were brought back to a hotel in Colombia by U.S. Secret Service and military personnel in an incident last week involving alleged misconduct with prostitutes, U.S. Senator Susan Collins said on Tuesday.
Collins was briefed by the director of the Secret Service, Mark Sullivan, on Monday evening. "There are 11 agents involved. Twenty or 21 women foreign nationals were brought to the hotel, but allegedly Marines were involved with the rest," the Republican senator said in comments emailed to Reuters.
The Secret Service on Monday said it had revoked the top security clearances of the 11 employees, who have been placed on administrative leave due to the incident that marred President Barack Obama's weekend trip to Colombia.
The agents brought a number of prostitutes back to a beachfront hotel in Cartagena, according to a local police source. A U.S. official told Reuters on Monday that more than 10 military service members also may have been involved.
"Director Sullivan is rightly appalled by the agents actions and is pursuing a vigorous internal investigation," she said. "He ordered all the agents to return to Washington immediately, and all have been interviewed."
The senator is the top Republican on the Senate Homeland Security Committee, which shares jurisdiction over the Secret Service with the Judiciary Committee.
Collins said she asked Sullivan several questions, including who the women were. "Could they have been members of groups hostile to the United States? Could they have planted bugs, disabled weapons, or ... jeopardized security of the president or our country?"
She also asked whether there was evidence of previous misconduct, and "given the number of agents involved, does this indicate a problem with the culture of the Secret Service?"
Sullivan had promised to keep her updated and Collins said she was confident he would fully investigate and "pursue appropriate action against the agents should the allegations prove true."
NBC News said that two Secret Service supervisors and three counter-assault team members were among the 11 employees implicated in the alleged misconduct in Colombia.
All Secret Service personnel had been given copies of Obama's schedule for the trip and were told to lock them in a safe in their hotel rooms, NBC said, citing a law enforcement source. That raised the possibility of a security breach when the agents allegedly brought prostitutes back to their rooms, NBC said.
A Secret Service source told Reuters that the employees involved in the scandal were support personnel and not part of the advance team, so they would typically not have detailed itineraries and schedules that far ahead of the president's arrival.
Also any such papers would not be left in the hotel room, but would be kept in a security room set up for foreign presidential trips, guarded by Marines around the clock.
"That kind of stuff is not kept in rooms," the Secret Service source said.
Republican Representative Peter King, who heads the House of Representatives Homeland Security Committee, told NBC's "Today" show that if the agents did have copies of the president's schedule, the incident "could have been disastrous."
"This violates the most basic rule of being a Secret Service agent: You don't allow a potential enemy into your security zone," said King, who added that he had not seen such behavior before from Secret Service agents.
A separate report on Tuesday from ABC News said Secret Service agents partying at a club in Cartagena boasted that they worked for Obama and were in Colombia to protect him.
(Additional Reporting By Emily Stephenson, Editing by Eric Beech)