Media playback is unsupported on your device Media caption Chris Christie avoided questions from the press as he left Howard Stern's 60th birthday party

New Jersey Governor Chris Christie knew about the closures of local lanes leading to a busy bridge to New York City while they were happening, a lawyer for a former ally has said.

David Wildstein said he had evidence to show Mr Christie knew about the lane closures, which caused a huge traffic jam at the George Washington Bridge.

Documents suggest the traffic jam was orchestrated by Mr Christie's aides.

Mr Christie on Friday reiterated he had "no prior knowledge" of the closures.

The scandal has damaged Mr Christie's standing as a potential candidate for the 2016 Republican presidential nomination.

'Evidence exists'

In a letter to the general counsel of the Port Authority of New York and New Jersey, which manages the George Washington Bridge and other bridges and tunnels between the two states, Mr Wildstein's lawyer wrote, "Evidence exists... tying Mr Christie to having knowledge of the lane closures, during the period when the lanes were closed."

The letter written by New Jersey lawyer Alan Zegas described the lane closure as occurring under "the Christie administration's order", and said Mr Wildstein suggested Mr Christie had not spoken truthfully in a January news conference.

Mr Christie said then that he had been "blindsided" by the revelations his aides were involved in the traffic jam.

"I had no knowledge or involvement in this issue, in its planning or execution," the governor said.

Image copyright AP Image caption Wildstein resigned after his involvement in the traffic jam was revealed in the news media

The four-day September traffic jam in the streets of Fort Lee, New Jersey, which sits at the foot of the bridge, is believed to have been orchestrated by Mr Christie's aides to punish its Democratic mayor for his refusal to endorse the governor in his 2013 re-election campaign.

The traffic jam was caused when workers closed off two local lanes from Fort Lee onto the bridge, ostensibly to conduct a traffic study.

State legislators and federal prosecutors have launched inquiries into the matter, and Mr Christie has pledged to co-operate.

Mr Wildstein, a high school friend of Mr Christie, was a senior political appointee on the Port Authority until he resigned in December as the probe into the traffic jam began gathering steam.

'No prior knowledge'

In January, Mr Christie sacked Bridget Anne Kelly, his deputy chief of staff.

"Time for some traffic problems in Fort Lee," Ms Kelly wrote on 13 August to Mr Wildstein, according to a copy of the email obtained by the news media in January.

"Got it," Mr Wildstein replied.

Mr Wildstein has refused to testify in legislative inquiries into the matter, citing his constitutional protection against self-incrimination.

In a statement released by his office to the news media on Friday, Mr Christie said Mr Wildstein's lawyer "confirms what the governor has said all along - he had absolutely no prior knowledge of the lane closures before they happened".

According to the statement, Mr Christie believed only that a traffic study was under way until he read "otherwise" on the morning of 8 January, when his aides' involvement was revealed in the news media.