WASHINGTON — The Secret Service prostitution scandal grew Monday to include a 12th member of the U.S. military as the Pentagon suspended the security clearances of all the military personnel who have been implicated.

The Secret Service has also taken action against 12 of its employees.

Three Defense Department officials said the 12th military person involved was in Colombia in advance of President Barack Obama’s arrival for the Summit of the Americas and was assigned to the White House Communications Agency, a military unit that provides secure communications for the president.

One of the officials said the serviceman has been relieved of his duties at the White House.

Meanwhile, the White House still faced fire Monday because of the prostitution scandal. It moved anew to keep itself at arm’s length in two ways.

Led by its top lawyer, the White House internally investigated and then ruled out misconduct by the White House staff members who helped arrange the president’s trip ahead of his arrival in Colombia. Obama’s chief spokesman, Jay Carney, sought to make clear that the White House Communications Agency, which has now been implicated by the widening scandal, is a military unit and not a White House one.

“These are military personnel, staffed by the military, they are not members of the White House staff, they are not chosen by the White House senior staff,” Carney said.