A NEW M4 would jeopardise conservation work to save the UK’s fastest declining mammal, the Gwent Wildlife Trust say.

As figures from a new report out by The Wildlife Trusts (TWT) reveal the UK has seen a 30 per cent decline in water voles.

Here in Wales, the work of Gwent Wildlife Trust (GWT) has seen the mammals brought back from local extinction.

However, GWT says Welsh Government plans for a new M4 across the precious Gwent Levels will undo their conservation work to help the UK’s fastest declining mammal, as the new motorway will destroy the rare wetland habitat where water voles live.

Plans for a motorway have been condemned by the charity, which say in ecological terms it is like destroying "Wales’ own version of the Amazon rainforest".

It also says the new motorway would result in the "demise of thousands of rare and endangered bugs, birds and other wildlife including our now well established water vole population, fragmenting the habitat and contaminating the ditches".

GWT’s deputy chief executive Gemma Bodé said: “Sadly, the proposed new M4 motorway ploughing across the Gwent Levels, will potentially halt and reverse the water vole recovery on the Levels and could lead to its sad extinction here, once again.”

In the early 2000s, it was thought that water voles were extinct on the Gwent Levels.

In 2012 with help from a Heritage Lottery Fund grant, GWT embarked on a reintroduction programme to return water voles to their native landscape.

They released more than 200 at their Magor Marsh nature reserve and now through careful monitoring and habitat management, they have spread in all directions and become well established once again on the Gwent Levels.

GWT and WTW gave evidence at the Welsh Government M4 Public Inquiry, in Newport last year. GWT and WTW are due to submit further evidence to the inquiry in March.