Government officials are probing the U.S. pilot who posted a number of videos on YouTube revealing security lapses at the San Francisco International Airport.

On November 28, the 50-year-old pilot, Chris Liu, posted a series of six videos on YouTube to show to the world what he considers as major security lapses at the airport.

The videos showed that while passengers undergo close scrutiny at the security check areas, ground crew staff swipe security cards and enter secure areas without undergoing any screening.

The sixth and final video was that of air marshals and sheriff's deputies who came to the pilot's home earlier this month to seize his gun. The pilot had been allowed to carry the weapon on board as part of a programme after the September 11, 2001 attacks that trains certain flight crew to serve as federal flight deck officers to prevent hijackings.

Don Werno of law firm Werno and Associates is representing the pilot who is still employed at the airline but has withdrawn from the programme against hijackings. He informs that the Transportation Security Administration (TSA) is looking into whether his client revealed sensitive information.

The TSA would not answer questions but said in a statement that it was responding to the situation and was confident of security at San Francisco Airport.

As to access control at SFO, TSA is confident in the tools the airport has implemented and reminds passengers there are security measures in place that are both seen and unseen, a statement by the TSA said.

Upon objection by TSA, Chris removed the videos from YouTube.