Eleven US Secret Service agents recalled from Colombia over an alleged sex scandal have had their security clearances suspended, a US government official said.
The agents were pulled back to Secret Service headquarters in Washington after claims that US personnel invited prostitutes to their rooms, proved an embarrassment at a weekend summit involving President Barack Obama.
The Pentagon said earlier that more than five US military personnel were also being investigated over alleged misconduct in the resort of Cartagena, the host city of the Summit of the Americas at the weekend.
The US source said on condition of anonymity that the agents, who have been placed on administrative leave, had their security clearances suspended pending an investigation into the allegations.
Obama said on Sunday that he expected a "rigorous" investigation into the alleged scandal, warning he would be "angry" if the claims -- reportedly also involving a dispute over payment to a prostitute -- were proven true.
The military is conducting a separate probe and has confined the service members involved to their barracks.
None of the Secret Service personnel involved -- both agents and uniformed officers -- was assigned to Obama's personal security detail.
The US military's most senior officer, General Martin Dempsey said earlier that defense chiefs were "embarrassed" over the incident.
"We let the boss down, because nobody's talking about when went on in Colombia other than this incident," said Dempsey, chairman of the joint chiefs of staff.
A Pentagon spokesman said the service members who are under investigation were not handling security for the US president but were performing important work in support of the Secret Service.
"We believe that there maybe more than five involved in this incident. I don't have specific numbers. We're going to look at the facts wherever they may go," spokesman George Little told reporters.
The personnel were from more than one branch of the military, and some of them were at the same hotel as other Secret Service agents alleged to have brought prostitutes to their rooms, he said.