The road is closed between the A417 and the A419. (Image: Supplied)
The A419 is partially closed at the junction with the A417 after an accident, causing congestion between Swindon and Cirencester.
Lane two has been shut heading northbound, between the junctions with the A4311 and the A417, according to Google Maps.
This follows a crash which was reported at around 4pm.
It is estimated that the lane will be cleared and the road will fully reopen between 6.30pm and 6.45pm.
The closure is currently causing tailbacks on the road from Swindon to Cirencester. Traffic is particularly heavy between the A417 and Cerney Wick.
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