Sex scandal: 3 secret service agents quit; Obama briefed

Three more US Secret Service agents have resigned over the sex scandal in Columbia, as President Barack Obama was given a briefing on the issue that has become an embarrassment for the White House and for the elite security agency.

Three employees have chosen to resign, the Secret Service said in a statement as it continued with its probe into the scandal.

With this, the total number of Secret Service agents who have lost their jobs after the scandal broke out is six.

Besides interviewing the personnel involved, Secret Service is also conducting lie detector tests.

"As a result of the ongoing investigation in Cartagena, a twelfth employee has been implicated.

"He has been placed on administrative leave and his security clearance has been temporarily suspended pending the outcome of the investigation," the Secret Service said in a statement.

One of the employees involved has been cleared of serious misconduct, but will face appropriate administrative action, it said.

At this point, five employees continue to be on administrative leave and their security clearances remain suspended pending the outcome of this investigation, the statement said.

The Secret Service continues to conduct a full, thorough and fair investigation, utilising all investigative techniques available to the agency, it said, adding that this includes polygraph examinations, interviews with the employees involved, and witness interviews, to include interviews being conducted by the Office of Professional Responsibility in Cartagena, Colombia.

"We demand that all of our employees adhere to the highest professional and ethical standards and are committed to a full review of this matter," it said.