WASHINGTON - The US Secret Service has placed 11 agents on leave due to alleged misconduct in Colombia's Cartagena, where President Barack Obama is attending a summit.

The Secret Service said in a statement Saturday that the measure is "standard procedure and allows us the opportunity to conduct a full, thorough and fair investigation into the allegations."

The statement gave no account of what was suspected to have occurred.

According to US media, the allegations related to the agents' activity before Obama's arrival Friday and involved prostitutes.

The statement said the incident is "not reflective of the behavior of our personnel" and the service regrets the distraction it created for the Summit of the Americas.

Officials said the agents have been replaced by other Secret Service personnel, and Obama's security plan would not be affected.