U.S. President Barack Obama said Sunday he expects a "rigorous" investigation into allegations of Secret Service misconduct in Colombia, warning that he would be "angry" if they were true.
The scandal overshadowed Mr. Obama's diplomatic work at the Summit of the Americas in Cartagena this weekend.
U.S. officials said Saturday that 11 Secret Service personnel sent to Colombia ahead of President Obama's visit were sent home and placed on administrative leave pending an investigation of alleged misconduct that involved prostitution. Five U.S. military staff assigned to support the Secret Service were confined to their barracks in Colombia.
The alleged misconduct is said to have taken place before Mr. Obama arrived in the resort city of Cartagena Friday for the Summit of the Americas.
Mr. Obama cast the incident as isolated and praised the Secret Service as a whole.
Earlier Sunday, a leading Republican in the House of Representatives said he believed the incident in Colombia was probably not an isolated incident.
California Representative Darrell Issa said, "Things like this don't happen once if they didn't happen before." Issa, chairman of a House oversight committee, told CBS television's Face the Nation program he did not know if Congress would hold hearings on the incident.
Of primary concern, he said, is that agents who misbehave are vulnerable to blackmail and therefore could risk the security of the president and others under their protection.
The Secret Service has said none of the personnel involved were assigned to protect Mr. Obama.