A PROPOSED M4 relief road would have an "immense and unprecedented" impact on habitats in the Gwent levels, a wildlife trust has warned.

Gwent Wildlife Trust, which is giving evidence over two days at the public inquiry, is calling on the Welsh Government to drop plans for the planned £1.1bn project.

On the first day of its evidence yesterday, professor Terry Marsden warned about the environmental consequences of the relief road. Mr Marsden, speaking on behalf of GWT, said building the road could solve “immediate needs” of traffic problems, but would have a damaging long-term impact.

“This is an issue of immediacy versus generations,” professor Marsden told the inquiry.

“We are no longer even talking about future generations. We are talking about our own children and grandchildren living to the end of the century. The potential predictions of temperature rise are absolutely catastrophic.”

Mr Marsden also raised concerns that Welsh Government environmental targets would not be met if the plans go-ahead. GWT has warned the relief road would have damaging impacts on all of the Gwent levels.

A spokeswoman for the trust said the effect on habitats would be “immense and unprecedented in Wales.”

Chief executive of GWT Ian Rappel, said: “In ecological terms the Gwent Levels is Wales’ very own version of the Amazon rainforest and should be protected for people and wildlife, now and for future generations.

He added: "The motorway would rupture the essential cohesion of the Gwent Levels, acting as an impermeable barrier to all flightless wildlife and a dangerous permeable barrier to flying wildlife such as rare bats and bumblebees.

"It would snap the protected habitat like a cracker in two, isolating wildlife populations on either side of the divide, devaluing the habitat on both sides of the motorway making both populations smaller and more vulnerable to local extinction.”

John Davies, on behalf of the Welsh Government, states in his evidence: “The scheme is necessary to address a current problem that requires action today in accordance with the sustainable development principle of the Well-being of Future Generations Act to prevent the situation getting worse and leaving it for future generations."