A car fire on Auckland’s Southern Motorway has left a lane blocked, creating a growing backlog of northbound traffic.

Emergency services were attending to the blaze, between the Princes St ramps and the Mt Wellington Highway ramps, about 2.40pm today.

A fire has left the charred remains of a car on Auckland's Southern Motorway, creating major northbound traffic backlogs ahead of rush hour on Wednesday.

Emergency service vehicles have blocked the left northbound lane to respond to the fire, Waka Kotahi NZ Transport Agency said.

The agency told motorists to merge to pass the wreckage and to expect delays.

Traffic had already started to pile up over 2km back only 10 minutes after the fire was reported to emergency services.

A passing motorist told the Herald she saw firefighters battling the blaze.

“I was driving from Panmure when I saw it. I just saw smoke. We thought it was from one of the houses - but by the time we got up to it, it was a car,” she said.

“We saw firefighters putting it out - and police there too.

“Traffic was crawling. The smoke has gone down now, so the traffic is calm now.”

Fire and Emergency NZ received multiple calls to the fire about 2.25pm.

The driver wasn’t with the car and hasn’t been found, a Fire and Emergency spokeswoman said.

The car was well involved in flames when firefighters first arrived at the scene, she said.