President Barack Obama says he expects the investigation of Secret Service misconduct in Colombia to be thorough and rigorous, and says he will "be angry" if the allegations turn out to be true.

The scandal involving Secret Service agents and prostitutes overshadowed Obama's diplomatic work at a major summit this weekend in Colombia. The alleged misconduct took place before Obama arrived.

Eleven Secret Service agents were sent home. Five U.S. military service members were also alleged to have been involved in the incident.

Obama said the men and women of the Secret Service perform extraordinary service for him, his family and U.S. officials.

He never directly mentioned the prostitution allegations but alluded to them, saying "of course I'll be angry" if they are proven true.

(Copyright 2012 by The Associated Press.  All Rights Reserved.)