Image caption More military members may be involved in the prostitution scandal than the five originally reported

Claims that Secret Service agents and military personnel hired prostitutes in Colombia are an embarrassment, the US military's top officer has said.

"We let the boss down," US Joint Chiefs of Staff Chairman Martin Dempsey told a Pentagon news conference.

Secret Service and military staff have been questioned over allegations of misconduct on the eve of President Obama's visit for a weekend summit.

Eleven Secret Service agents have been suspended and sent home.

A senior official told the BBC that at least 10 military service members were under investigation. A Pentagon spokesman said earlier there were more individuals involved than the five originally reported.

Distraction

Gen Dempsey said the military did not know exactly what had happened in the Colombian city of Cartagena, where President Barack Obama attended the Summit of the Americas over the weekend.

"What we do know is that we distracted the issue from what was a very important regional engagement for our president," he said.

"So we let the boss down. Because nobody is talking about what went on in Colombia other than this incident."

"We are embarrassed," Gen Dempsey added.

On Sunday, the US president said that he expected a "rigorous" investigation.

"If it turns out that some of the allegations that have been made in the press are confirmed, then of course I'll be angry," Mr Obama said.

US Southern Command said military staff had been supporting the Secret Service during the summit, staying at the same hotel as the agents.

According to Mr Little, the Secret Service and military staff in question were not directly involved in presidential security.

Image caption Defence Secretary Leon Panetta said those involved would "be held accountable"

According to Reuters news agency, a policeman in Cartagena said at least one Secret Service agent had attempted to take a prostitute up to a hotel room without registering his guest at reception.

Gen Douglas Fraser, commander of the Southern Command, said he was "disappointed by the entire incident and that this behaviour is not in keeping with the professional standards expected of members of the United States military".

In a statement on Saturday, the Secret Service said 11 employees had been put on administrative leave, and apologised for the distraction caused by the incident.

The 11 employees included both special agents and Uniformed Division officers, the agency's assistant director said.

A spokesman for the US Southern Command declined to say how many military members were under investigation or what branch they were from.