The man who scaled the Sydney Harbour Bridge on Wednesday and sent roads into gridlock has tried to grab an officer’s gun while under police guard in hospital.

Wayne Cook, 44, was under the influence of ice when he climbed the iconic attraction at 4.30am on Wednesday, News Corp Australia reports.

CCTV cameras captured Cook riding a push bike along the Harbour Bridge before abandoning it and scaling a security fence.

The man was sitting precariously on the bridge beams with police for around five hours. (AAP) (AAP)

CCTV cameras captured Wayne Cook riding a push bike along the Harbour Bridge before abandoning it and scaling a security fence. (9NEWS)

Traffic was banked up 30 kilometres heading southbound into the city, costing Sydney’s economy millions in lost productivity.

After the five-hour stand-off, police negotiated with the Woolloomooloo man to come down and he was taken to St Vincent’s Hospital with “significant mental health issues”.

Police negotiators were able to bring the man down to safety about 10am. (AAP) (AAP)

It is understood while in hospital, Cook allegedly tried to grab a police officer’s gun and was restrained, the Daily Telegraph reports.

Superintendent Michael Fitzgerald said Cook was known to police, had “significant mental health issues” and climbed the bridge due to a “family issue”.

"We were concerned that he was going to harm himself but also we were concerned about what harm could have been occasioned to innocent members of the public driving underneath him,” Supt Fitzgerald said.

The five-hour standoff caused traffic gridlock on the Sydney Harbour Bridge and across the city. (9NEWS) (Supplied)

Cook is expected to face charges for both incidents when he is released from hospital.

A $3000 fine is issued to people who illegally climb the bridge without authorisation.