Armed private contractor was allowed on elevator with Obama: Reports
US President Barack Obama comments on the situation in Ukraine following a tour of a classroom at Powell Elementary School on March 4, 2014 [AFP]

An armed private security agent was allowed on an elevator with President Barack Obama earlier this month in Atlanta, a Secret Service official said on Tuesday, in another case involving a security failure for the embattled agency.

The incident occurred while Obama was visiting the U.S. Centers for Disease Control and Prevention on Sept. 16, three days before a man with a knife jumped the White House fence in Washington and ran into the executive mansion.

The White House intrusion has sparked sharp criticism of the agency responsible for protecting the president. Secret Service Director Julia Pierson told a congressional committee on Tuesday: "This is unacceptable and I take full responsibility."

In the Atlanta incident, first reported by the Washington Examiner and Washington Post, a security contractor with the CDC was operating the elevator carrying Obama and his Secret Service detail.

The man began taking pictures and video of Obama on his phone, prompting the Secret Service to take him aside for questioning after they left the elevator, the agency official said.

It was not until his supervisor appeared and asked for his gun that the Secret Service realize he was armed, the official said. Under agency rules, people with access to the president need special clearance to carry guns.

The Washington Post reported that a background check also showed the man had three previous convictions for assault and battery.

The Secret Service official said the probe of the incident was part of an ongoing investigation by the agency.

(Reporting by Steve Holland; Writing by Peter Cooney; Editing by Ken Wills)