An accident in the Brynglas Tunnels in the early hours of this morning means the M4 Eastbound is closed near Newport.
The motorway's shut between Junctions 28 and 25A; Tredegar Park and the Grove Park Roundabout.
Traffic is queueing for around four miles back to J30 the A4232 at Cardiff Gate and on the A48(M) to J29a at St Mellons.
There's a diversion on the Southern Distributor Road where traffic's very heavy.
Police say they hope to re-open the motorway by 9am.
More top news
Dyffryn Gardens is one of five locations battling it out to be crowned the best place in Wales in this year's Special Places competition.
Retired game-keeper Raymond Arthur Evans’ passion for guns landed him in hot water. Nursing home staff even found a pistol in his room.
RSPCA Cymru says it's worried about a rise in reports of pets being poisoned. Here's the charity's advice on how to keep your animals safe.