Peak hour commuter chaos as a crash on the Sydney Harbour Bridge shuts down four lanes and causes kilometre-long traffic jams

A serious head-on crash on the Sydney Harbour Bridge has sparked major delays for peak hour traffic.

Three southbound lanes and one northbound lane have been closed following the crash at around 6am Monday morning.   

A NSW Police spokeswoman said no one was seriously injured in the two car crash.

A head-on crash sparked traffic chaos on the Sydney Harbour Bridge on Monday morning

The crash has sparked heavy traffic queues stretching for over a kilometre for motorists heading to work in the CBD

One motorist said traffic is now moving again after 40 minutes stationary. 

Bus commuters should also expect a longer trip into work with delays of up to 35 minutes. 

The two car crash occurred in a southbound lane around 6am on Monday. Pictured are emergency services at the scene

All southbound lanes have since reopened while one northbound lane remains closed.

A vehicle salvage operation is now underway with tow trucks at the scene. 

Live Traffic Sydney urges motorists to use an alternative route and to allow extra travel time.

Five NSW Ambulance crews attended the scene and treated two men aged in their 30s. 

One was treated for a suspected medical episode and transported to St Vincent's Hospital in a stable condition

Commuters heading into the city via the Sydney Habour Bridge should expect major delays

The other was treated for minor injuries and transported to Royal North Shore Hospital in a stable condition.

'Thankfully both patients didn't suffer any life-threatening injuries,' NSW Ambulance Inspector Kay Armstrong said.

'We need to be cautious on the roads over the Christmas break. These type of crashes have the potential to be fatal.'