A GWENT AM has said he is concerned the cost of the proposed M4 relief road will "spiral" after it was announced the scheme's pricetag had increased again.

Yesterday the Argus reported first minister Carwyn Jones had refused to answer questions around whether there is a maximum cost for the so-called black route project. He was speaking after it was revealed the predicted cost of the scheme had increased to up to £1.4 billion, and will go up again once VAT is taken into account.

And yesterday Monmouth AM Nick Ramsay quizzed the Welsh Government's finance secretary Mark Drakeford over the scheme, saying: "Are you prepared to give details of a cap, or is the Welsh Government happy for the costs simply to spiral?"

Mr Drakeford replied he was not prepared to make any comments around the cost of the scheme while a public inquiry, which will resume next week, is in progress.

He added: "I remain confident that, should the scheme get the go ahead as a result of the independent local public inquiry, I will be able to use the levers available to me to be able to put the scheme into practice."

But Mr Ramsay said he was "becoming increasingly concerned" about the lack of financial figures around scheme and called for a review of the costs.

"It wasn't that long ago that the Welsh Government told the Assembly that the cost would be less than £1 billion," he said. "I think a guarantee of some form was issued to us, whether it was that word or not, back then.

"But it now seems that this was grossly underestimated.

"If you look at examples of other large road schemes in Wales, such as the A465 Heads of the Valleys widening, that has been subject to many delays and is currently costing an estimated 25 per cent over the original budget.

"So, you can understand the public's concern about these kinds of projects."

He added: "The M4 black route will, if chosen, run through sites of special scientific interests and across wetland, making it more complex than many other road schemes would be.

"Do you not think that, aside from the public inquiry, it's time for a full review of the potential costs of this project to ensure value for money for the taxpayer?"

Mr Drakeford replied: "I share (Mr Ramsay's) concerns that spending plans right across the Welsh Government are implemented in the most efficient and cost-efficient way.

"That would apply to this scheme in exactly the same way as it would apply to all other ways in which capital investment available to the Welsh Government is paid out in practice."

The so-called black route, which involves a new piece of motorway running south of Newport, bypassing the Brynglas Tunnels, is the Welsh Government's preferred solution to traffic problems on the M4.

But the predicted cost of the scheme has continued to rise. Last month it was revealed it had increased again by £136 million following a series of new measures at Newport Docks.

The public inquiry, which will resume on Wednesday, January 31, is looking at all options. Among them is the so-called blue route, which involves turning the Southern Distributor Road and the Steelworks Road into a dual carriageway.