WASHINGTON - Three Secret Service agents have been forced out of their positions in the aftermath of a scandal involving 11 agency personnel and prostitutes during a presidential visit to Colombia.

The decision was announced Wednesday by Paul Morrissey, the assistant director of the agency's Office of Government and Public Affairs, in a written statement.

"Although the Secret Service's investigation into allegations of misconduct by its employees in Cartagena, Colombia, is in its early stages, and is still ongoing, three of the individuals involved will separate or are in the process of separating from the agency," said the statement.

One supervisory employee was allowed to retire and another was "proposed for removal for cause," the statement said. In addition, a non-supervisory employee resigned.

The employee proposed for removal has been given notice and will be allowed to fight the move, the Secret Service said.

Eight other Secret Service employees remain on administrative leave with suspended security clearances. In addition, some Secret Service personnel are now under investigation for possible drug use.

Eleven agents were alleged to have engaged in misconduct in Cartagena, where President Barack Obama attended a weekend summit. According to US media reports, the allegations related to activity involving the agents before Obama's arrival Friday, and the allegations involved prostitutes.