New Jersey Governor Chris Christie knew more than he has admitted about a plot to close bridge lanes to spite a rival, US media reported tonight.

Mr Christie is a frontrunner for the Republican party's presidential candidacy, but his image as a blunt-spoken man of the people has been threatened by the "Bridgegate" political dirty tricks scandal.

The New York Times and the Wall Street Journal have reported that a former local official has said that the order to close the bridge came from the "Christie administration".

David Wildstein, a former senior Port Authority official who had known Mr Christie at high school, also said that Mr Christie was aware of the lane closures as they were causing traffic chaos.

"Evidence exists... tying Mr Christie to having knowledge of the lane closures, during the period when the lanes were closed, contrary to what the governor stated publicly in a two-hour press conference," lawyer Alan Zegas said in the letter to the Port Authority.

Mr Wildstein personally oversaw the bottleneck, which was allegedly triggered deliberately in order to punish a local mayor who had failed to endorse Mr Christie's re-election campaign.

Although Mr Christie has denied knowing of the closures, he has admitted that aides may have ordered them for political reasons.

Mr Zegas's letter also challenged the Port Authority's decision to not pay Mr Wildstein's legal fees in connection with probes into the George Washington Bridge access lane closures.

As a result of the closures, local commuters faced massive traffic jams in Fort Lee New Jersey in September.