THE proposed M4 relief road would cause “unprecedented” damage to the environment around Newport, a group of 10 Welsh charities has claimed.

The organisations have written an open letter to the Welsh Government’s newly-appointed economy and infrastructure secretary Ken Skates calling on him to scrap the plan.

In the letter the charity's chief executives say they have serious concerns around the damage the scheme would cause to the Gwent Levels and the River Usk Special Area of Conservation, home to wildlife including waterfowl, otters, voles, bats and rare insects.

“The habitat loss, combined with the landscape and visual impact on the Gwent Levels and its surroundings, would not only be brutal but irreversible,” it said.

“The proposed scheme potentially represents ecological destruction on an unprecedented landscape scale and one of the most damaging developments in recent history.”

The letter is signed by the chief executives of Wildlife Trusts Wales, the Campaign for the Protection of Rural Wales, Buglife, the Campaign for Better Transport, Butterfly Conservation Wales, the Bat Conservation Trust and Sustrans Cymru as well as the Welsh branches of Friends of the Earth and the RSPB.

The letter continued the plan was approaching road problems around Newport and in south Wales “in the wrong order”.

“Increasing road capacity should be the option of last resort, not the first,” it said.

“The government’s first priorities must be to enhance the potential of rail freight and improved public transport to meet future transport needs, including electrification plans for mainline rail and the expanded Metro serving the region around Cardiff and Newport.

“The Welsh Government’s Active Travel Act could also deliver the kind of transformative change in travel behaviour needed to meet the government’s emission reduction and health targets, if the political will and necessary finance is forthcoming.”

The charities also said they were in favour of the alternative ‘blue route’, which involves converting the A48 Southern Distributor Road and the former Steelworks Road in Newport into a dual carriageway, claiming it could be completed faster than the Welsh Government’s preferred ‘black route’.

“We do not agree nor do we consider that the black route would deliver sufficient benefits to justify or outweigh the environmental and financial costs of the currently proposed route,” they said.

“To the contrary, it will undermine key Welsh Government policy goals and legislative targets on environmental protection, modal shift, carbon reduction, air pollution and public health.”

The black route, which involves creating a new section of motorway south of Newport, is expected to cost £1.2bn. Work is currently scheduled to get underway in spring 2018, with the new road to open in autumn 2021.

A Welsh Government spokesman said: “The M4 relief road is hugely important to our vision for a fully integrated transport system for Wales.

"The next stage in the process will be to move to a public local inquiry which will consider a wide range of issues including alternative proposals.”