The U.S. Secret Service has recalled some of its agents providing security for President Obama in Colombia due to “allegations of misconduct.”

The agents were assigned to protect Mr. Obama during his talks with Latin American leaders and participation in the Summit of the Americas in the Colombian port city of Cartagena.

The alleged misconduct is said to have taken place before Mr. Obama arrived in Colombia Friday, but government officials disclosed no other details. The Washington Post reported that 12 agents were recalled from Cartagena, and that at least one was accused of involvement with prostitutes there.

The president of the Federal Law Enforcement Officers Association, Jon Adler, told the Post the prostitution charge is being investigated by the Secret Service, and that other agents working in the same team also were recalled.

A Secret Service spokesman, Edwin Donovan, said replacements were called in for the agents ordered to leave Colombia, and he added there had been no effect on security plans for the president's trip.

The Washington Post said it learned of the incident from Ronald Kessler, a former Post reporter and author of a book on the Secret Service. Kessler said he was told that 12 agents were removed from Colombia.