A judge has ordered a mental health evaluation for the man accused of scaling the White House fence and running into the building with a knife, The BBC reported on Tuesday.

Omar Gonzalez, 42, has pleaded not guilty to several charges stemming from the incident.

He was tackled inside the White House on September 19, and 800 rounds of ammunition, two hatchets and a machete were found in his car, officials say.

A screening that day suggested he was not competent to stand trial.

On Tuesday, a federal judge in Washington ordered him to undergo a 30-day mental health evaluation, delaying the court proceedings.

His attorney David Bos maintains his client will ultimately be declared fit to stand trial.

Prosecutors say Gonzalez jumped the main fence around the White House, dashed across the lawn and gained entry through an unlocked door, then barrelled past a guard and ran into the East Room before being tackled.

President Barack Obama and his family were not at the White House when the intrusion happened, having departed about 10 minutes earlier by helicopter.

It was later revealed that Gonzalez got far further into the building than initially said.

Officers found two powerful rifles, four handguns and other firearms and ammunition in his vehicle along with a map marking the White House, according to The BBC.

In addition, it has been reported Secret Service agents interviewed Gonzalez twice during the summer but concluded he was not a security threat.

The revelation of the security breach was followed by another revelation, that Obama rode an elevator with an armed security contractor who had three criminal convictions.

Julia Pierson, the director of the Secret Service, resigned her post after these incidents were exposed.