A commuter traffic jam has been cleared in the Sydney Harbour Tunnel after a car caught fire and backed up traffic for several kilometres on Tuesday morning.

The car burst into flames in the northbound lane of the tunnel about 9am, triggering sprinklers.

Both tunnel lanes were closed, with traffic backed up all the way down to Darlinghurst.

Emergency services said the driver managed to escape the car without any injuries, and no one else was hurt.

The tunnel was reopened in both directions just after 10.30am, but emergency services urged drivers to find other routes to cross Sydney Harbour.

Drivers took to social media to share vision of the flames, as onlookers got out of their cars to see the smoking vehicle.

Manly Sea Eagles footballer Martin Taupau was close to the action, posting a video showing vehicles jammed in the tunnel.

“If you’re heading to harbour tunnel, steer clear!” he wrote on Twitter.

Police said they believed the fire was sparked by a malfunction with the car. Officers are continuing to investigate.

-ABC