Published reports have revealed that US President Barack Obama rode an elevator this month with an armed security contractor who had three criminal convictions, a violation of Secret Service security protocols.

The Washington Examiner and the Washington Post reported on Tuesday that the latest incident took place in an elevator during Obama's September 16 visit to the Centers for Disease Control and Prevention in Atlanta.

The latest embarrassment for the Secret Service, which protects the president, comes after agency Director Julia Pierson took full responsibility for a September 19 breach of the White House.

The Post said agents questioned the contractor and discovered his criminal history after he refused to stop video recording the president with a phone camera.

Agents did not know he was armed until a supervisor fired the contractor on the spot, and the man turned over his gun.

The Secret Service did not immediately respond to an email request for comment sent by the AP news agency.

White House intruder

On September 19, an intruder armed with a knife, jumped a fence and sprinted across the White House lawn, and managed to enter the presidential residence's East Room, just minutes after Obama and his daughters left by helicopter from the South Lawn, for the presidential retreat at Camp David in Maryland.

The Post also revealed that it took the Secret Service five days before realising a man had fired shots at the White House in 2011, while one of Obama's daughters was inside.

First Lady Michelle Obama was reported to be furious about the incident which took place when she and her husband were out of town.

In all, at least seven bullets struck the upstairs residence of the White House, fired from a car parked about 600 metres away across the South Lawn.