Plans to build a motorway across an ecologically sensitive marshland in Wales have met with protests at the Welsh Assembly building in Cardiff.
Campaigners outside the Senedd called on Deputy First Minister Ieuan Wyn Jones, the transport minister, to scrap a proposed 14-mile stretch of road around the south of Newport.
The new route is intended to relieve traffic at notorious bottlenecks on the M4 near the city.
But conservationists said the road across the Gwent Levels marshland would harm wildlife and pollute sites of special scientific interest.
The Assembly Government finally unveiled plans to build the road in 2004, years after it was first proposed. At the time, officials said it could be a toll road with satellite tracking used to charge motorists.
Julian Branscombe, from the Campaign Against the Levels Motorway (Calm), said: "We want to make sure that the Assembly think again about this huge investment as something that is very damaging. It would take investment away from sustainable transport."
He said birds, rare plants and more than 150 species of invertebrates could lose their habitat if the road went ahead.
An Assembly Government spokesman said the business case for the road was being looked at and that a series of studies, required by law, would be considered to assess its environmental impact.
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