The A31 is closed on the eastbound carriageway at Ringwood, on the Dorset and HAmpshire border.
The road is closed between the A338 Salisbury Road turn off at Ringwood and The Mount turn off at Poulner.
Tailbacks are forming back to St Ives and motorists are advised to find an alternative route.
the road closure is also causing heavy traffic and delays on the A338 Spur Road at the Ashley Heath Interchange andf the A338 heading into Ringwood.
Hampshire Police has been contacted for more information