TWO former Welsh Government ministers spoke out against their own party tonight, when a motion by Plaid Cymru calling on Welsh Government to reconsider the alternative "blue" route for the M4 relief road was defeated.

The motion by Elin Jones AM proposed that the case has not been made for proceeding with the "black" route through the Gwent Levels, and that committing the entirety of new Welsh borrowing powers to one project will limit investment elsewhere.

It called on Welsh Government to fully consider the "blue" route on economic, traffic management, environmental and financial grounds.

It was defeated by 36 votes to 14.

The "blue" route is being backed by Plaid Cymru and environmental campaigners Friends of the Earth Cymru who have submitted a legal challenge to the government's chosen black route. They say Welsh Government did not consult properly on the alternative options.

Rhun ap Iorwerth AM opened the debate by stating that the M4 in the Newport area is a problem with regular congestion being bad for business and a serious inconvenience for hundreds of thousands of motorists.

He said minister Edwina Hart's decision at the end of summer term to push ahead with the black route was "hard to scrutinise" and said: "The immediate response from several members of her own back benches would've left her in no doubt of the strength of feeling (on the issue). That has since been amplified by others the length and breadth of Wales.

"There is a clear feeling it was the wrong decision," he said.

Blaenau Gwent AM and former environment minister Alun Davies, who was sacked earlier this year, said: "I will be supporting the government in the voting this afternoon but I wish to make it clear that I do not support the government in this decision.

"It's the wrong decision done in the wrong way and we need to re-examine (it).

"Others on this back bench described their own disappointment with the way the decision was reached and announced. I will do no more than to simply say I share their disappointments and this is not the way in which decisions should be taken or announced to this Assembly."

The AM said he was not an "instinctive anti-road person" but said his constituents in Blaenau Gwent would not benefit from the relief road, calling instead on the government to prioritise the South Wales Metro system idea.

Former culture minister John Griffiths AM, member for Newport East said a new road through Gwent Levels would be "incredibly damaging".