WALES' roads boss has blamed "incompetence" within the Department of Transport for delays to the M4 relief road project.

On Monday, the Welsh Government's economy and infrastructure secretary Ken Skates announced a public inquiry into the long-awaited scheme - previously due to begin next month - had been put on hold until next year. He placed the blame at the feet of the Department for Transport, which he claimed had introduced a new method of predicting traffic levels without informing the Welsh Government it was going to do so.

Speaking in the Senedd today, Mr Skates called the delay "hugely disappointing".

"I imagine the motorists who regularly use the M4 are absolutely fuming about this unnecessary delay," he said.

"The public deserve an explanation for this.

"I don't believe there is a conspiracy against Wales, but I do believe there is incompetence."

But the Department for Transport has refuted the claims, saying the Welsh Government had been informed of the change in the spring.

A spokesman said: “We keep our traffic forecasts under review and made clear to Welsh officials at the start of this year we were going to update our projections,” he said.

“We are committed to working closely with the Welsh Government and encourage them to deliver this project.”

Saying the UK Government had done "a huge disservice" to Wales, Mr Skates said that, although he had been aware the change was ahead, he had only been given three days notice that it was being introduced, saying this would normally be announced around a year in advance.

Saying he uses the motorway around four times a week, South Wales East AM Mohammad Asghar said he was concerned the project had been "kicked into the long grass".

"If I leave before seven o'clock it takes me still more than 40 minutes from Newport to this place (the Senedd)," he said.

"Lord help those who come after 7.30am and spend more than one hour on the M4 just to reach Cardiff, only 10 to 12 miles."

The Conservative AM, known more commonly as Oscar, also criticised Mr Skates for blaming the Department of Transport for the delay and said he was concerned about the impact on the areas economy.

"Poor transport infrastructure and lack of capacity means the South Wales corridor is not fit for purpose and is discouraging businesses locally nationally and internationally from investing in Wales," he said.

Plaid Cymru South Wales West AM Dai Lloyd also said he was concerned a decision made by the UK Government could have such an impact on a Welsh Government project.

"People have been waiting years for an improvement or for something to be done, he said.

"It is time for action."

The inquiry, expected to last around five months, will begin by the end of March 2017 and Mr Skates has said the project will still be competed on schedule by 2021.