A five-mile stretch of the Heads of the Valleys road will be closed in both directions this weekend.

The strip between Brynmawr, Blaenau Gwent, and Gilwern shuts at 8.30pm tonight, before reopening at 6am on Monday.

Part of a four-year project revamping the road into a dual-carriageway, the £800m project is due for completion late next year.

The Welsh Government described the route as "a crucial artery of our transport network and the principal road link between west Wales and the Midlands".

Motorists are being advised to take a diversion via Pontypool and Abertillery on the A467 and A4042.

The upgrade work involves widening the existing road which passes through Clydach Gorge, considered one of south Wales’ most important "environmental and ecologically sensitive areas".

The Welsh Government says the road improvements will improve safety and journey times.