WORK to widen a section of the A465 Heads of the Valleys road between Gilwern and Brynmawr could face further delays.

A legal dispute between the Welsh Government and project contractors Costain could put back the completion date until the first half of 2021.

The matter is the latest setback for the project to widen the A465 through the Clydach Gorge area, which has been affected by several delays and spiralling costs.

Costain said a dispute over responsibility for design information had originally been decided in their favour, but that the matter had been taken to arbitration.

The Welsh Government confirmed that the arbitration award, received in December, was a partial reversal of the earlier decision, though declined to reveal any more details of the decision due to "commercial confidence".

But Costain said the arbitration award "effectively splits the responsibility for the design information between both parties".

The firm said it was in talks with the Welsh Government over a financial settlement, but expected its operating profits to shrink, delaying the A465 completion date.

A Welsh Government spokesman said the project's budget - £324 million) has not changed.

“We are reviewing how the project can be concluded within the terms of the contract," he added. "This review is nearing completion and [transport minister Ken Skates] will make a further statement in due course.”

In November, the Argus reported how building work and diversions were causing misery for residents living near the roadworks, with one man saying disruption was "turning into a way of life".

A Welsh Government spokesman said today: “The dualling of the A465 from Gilwern to Brynmawr is an ambitious and challenging project which will deliver significant benefits when complete. We remain grateful to those living and working in the area for their patience while the works are ongoing.”