UPDATE 9.39am: Traffic has now returned to normal and the cars involved have been recovered.

UPDATE 8.33am: Traffic continues to tail back on both the M4 and A48(M) eastbound after the earlier crash.

Eastbound traffic via the A48(M) is now affected as far back as Newport Road in Cardiff.

UPDATE 8.06am: Traffic continues to tail back on the M4 eastbound following the earlier crash between junctions 29 (A48M) and 28 (Tredegar Park).

The queue is currently back more than thre miles to around junction 30 (Cardiff Gate) on the M4, while the A48(M) eastbound is tailed back several miles, to the Llanedeyrn roundabout.

UPDATE 7.59am: The vehicles involved in the crash are now all on the hard shoulder, and all lanes have been reopened eastbound.

UPDATE 7.55am: The ambulance service is now at the scene of the crash.

A CRASH involving four cars has blocked one lane of the M4 and partially blocked a second, eastbound approaching Newport.

The incident happened between junctions 29 (A48M) and 28 (Tredegar Park). Lane one (Of three) blocked.

Traffic is very slow as a consequence on the A48(M), approaching junction 29, with the queue stretching back some two miles.

Traffic is also backing up on the M4 westbound, approaching the crash site.