Update: 4.25pm

The road has now re-opened, police have confirmed. 

.  . . 

A SECTION of the Southern Distributor Road has been closed due to an obstruction on the carriageway. 

The A48 East Dock Road is both ways closed due to an obstruction on the road between A48 Spytty Road / B4237 Corporation Road (Corporation Road Traffic lights) and Nash Road (Nash Road Roundabout).

A motorist said police are diverting traffic through Corporation Road and that it is "extremely busy."

A spokeswoman for Gwent police said the road has been closed while Network Rail assess the railway bridge.