The environmentalists have produced a 30-page critique of the recent IWA report which called for large investment along the main A470 north-to-south-Wales trunk route in order to reduce driving times.

The question of road links between north and south Wales has become a political issue in the wake of the setting up of the National Assembly for Wales.

Rail link goes through England

At present, a coast-to-coast road journey can take anything upwards of four hours, due to the mountainous territory of mid Wales. The only rail link between north and south Wales actually runs through England.

The growth of the Assembly in Cardiff has heightened calls for improved transport links, and the IWAs' report was a response to this.

However, FoE Cymru said the institute's proposals were detrimental to road safety, were socially exclusive and would encourage traffic growth.

It says National Assembly should invest in providing an express rail service to link north and south.