UPDATE: 11.20am

There's congestion up to the  A4137 junction.

UPDATE: 8.38am

A South Wales Fire and Rescue Service spokeswoman has said that the fire has been put out.

She said that crews from Monmouth attended to the fire.

UPDATE: 8.30am

The car on fire has also been involved in a crash. 

8.20am

A car fire is blocking the A40 between the Gibraltar Tunnels and Raglan.

Traffic is blocked and stationary westbound between the tunnels at Mitchel Troy and Raglan.