How dopey can you get? By anyone's standards, it was a serious lapse of judgement.

A privately-owned Cessna aircraft that entered the same Los Angeles airspace as Marine One while the helicopter was ferrying President Barack Obama was intercepted by two fighter jets yesterday.

But after the small plane landed at Long Beach Airport, police then discovered it contained about 40 pounds of marijuana, a law enforcement official said.

The Secret Service said the president was never in any danger, despite the emergency procedure to remove the unauthorised aircraft from 'restricted airspace'.