South Norfolk Police say recovery of a lorry carrying sawdust is proving 'difficult' on the A140.
Police, who were called at 12.10pm, are currently on the scene of the accident at the Pulham Market roundabout on the Norfolk and Suffolk border.
A tweet by South Norfolk Police shortly before 2pm said that recovery will start shortly and long delays are expected. The road is expected to be closed for around 90 minutes.
At 4pm one south-bound lane was still closed and police said that while the road remains open it is likely to close before 5pm for up to an hour.
Travellers have been asked to plan journeys 'accordingly'.
There have been minor injuries.
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