TRADE at Newport Docks could be severely affected by a new £1 billion M4 relief road to the south of the city, Associated British Ports (ABP) has said.

With a new section of motorway built between Magor and Castleton including a bridge over the Usk, the docks could lose land and one of the docks could see height restrictions imposed on up to 60 per cent of the vessels using it, Matthew Kennerley, from the ABP said.

Mr Kennerley added he did not think it was a good idea to plan the new route through Wales’ most important general cargo port.

He said that throughout the consultation process, ABP had argued that a route slightly further north would be preferable.

The decision could threaten jobs and investment at the site, he added.

A broad coalition of groups has come out against the so-called ‘black route’ through the Gwent Levels, with the RSPB and Gwent Wildlife Trust among those advocating the ‘blue route’ of upgrades to the Southern Distributor Road as a better option.

Discussion of a road to relieve the bottleneck at the M4 in Newport has been ongoing since the 1991, when Welsh Secretary David Hunt announced a new motorway would be built.

The road is now earmarked for completion in 2022. There may now be legal challenges to the decision, which was announced on Wednesday.

A Welsh Government spokesman said: “We are committed to this ambitious infrastructure project, which has strong backing from business in Wales. The M4 project is of vital importance to the economic prosperity of the country as a whole.”