BIRDS of a feather stick together and down on the Gwent Levels that means shelducks, shovelers and pintails, redshanks, skylarks and curlews.

Look in the reens - the ancient man-made ditches designed to turn salt marsh into farmland - and you'll find beetles, molluscs, flatworms, leeches, water voles and crested newts.

And if that's not enough, check out the rare plants like mare's tail in the pond, meadow thistle and sedges.

This natural wonderland, one of the best eco systems of its kind in Britain, is the reason environmentalists are hopping mad over potential developments like the M4 Relief Road.

From the east, the six-lane relief road would start at junction 23, running north of Magor before sweeping down on to the Gwent Levels and running south of Llanwern Steelworks.

It would cross Uskmouth and the docks on an elevated section supported on giant stilts before resuming its course across the levels at Wentloog. The road would rejoin the main M4 at junction 29 (Castleton).

Backers, which include Newport council, Newport and Gwent Chamber of Commerce and the South East Wales Economic Forum believe the relief road will be great for the city and great for South Wales.

They believe that economic prosperity is being held back by the constriction of the motorway at Brynglas Tunnels.

The National Assembly has watched England sort out its main motorway problem by commissioning the North Birmingham Relief Road on the M6 and it wants do the same at Newport.

The half-a-billion pound price tag could be met by the public purse, the private sector (repaid by tolls) or a combination of the two. But Friends of the Earth Cymru is set firm against the project. Neil Crumpton, the group's transport spokesman, spoke to the Argus yesterday, before his meeting with National Assembly economic development minister Andrew Davies.

He said: "The scheme may attempt to use brownfield land where it can, but it will still be disruptive to a unique area of special scientific interest." He also pointed out that the scheme could use up the entire Assembly road-building budget for the next eight to ten years, leaving nothing for the rest of Wales.

"It will encourage much greater use of the car and more long-distance commuting. And it will take people off the railways and put pressure on adjacent roads - look at the traffic problems in Chepstow, for example."

Mr Crumpton thought a high-speed motorway option might also encourage Welsh people to go shopping in English shopping centres such as Cribbs Causeway. "So the projected economic benefits may not be so great."

If the Assembly does publish new proposals he wants it to undergo full public consultation and dialogue and includes alternative schemes. "It's too late once you get to the public inquiry stage because they are too adversarial to explore all the options properly."