WASHINGTON - US media on Friday evening reported a dozen Secret Service agents accompanying President Barack Obama on a visit to Colombia's Cartagena for a summit were sent home for alleged misconduct.

MSNBC reported the allegations before Obama's arrival in Cartagena Friday afternoon. The agents were replaced by other Secret Service personnel, and Obama's security plan wouldn't be affected.

Those involved in the allegation were relieved of duty and sent back. The matter is now handled by Secret Service's Office of Professional Responsibility. Media reports said the allegations involved prostitutes.

Obama is in Cartagena for the sixth Summit of the Americas, which is to be held over the weekend.