A prominent U.S. newspaper is reporting that U.S. Secret Service agents sent to Colombia to provide security to President Barack Obama have been recalled amid allegations that they solicited prostitutes. The president arrived in Cartagena Friday to attend a regional summit.

The Washington Post says while seeking the services of a prostitute is not illegal in Colombia when conducted in designated zones, such behavior is deemed inappropriate by the Secret Service.

The newspaper says it was made aware of the allegations by Ronald Kessler, a former Washington Post reporter and author of the book In the President's Secret Service. Kessler said 12 agents have been removed from the Colombia trip. He said several of the agents are married.

Edwin Donovan, a Secret Service spokesman, would not confirm how many agents were removed from the president's security detail or whether allegations of prostitution were involved in the withdrawal of the agents from Colombia.

Donovan says the agents have been replaced by other agency personnel and the investigation has been turned over to the Secret Service internal affairs unit.