THE M4 relief road could be "thrown in the bin" as a result of the election of a new first minister, Wales' top Tory has warned.

Andrew RT Davies has said he is concerned the forthcoming election of a new Welsh Labour leader and first minister after Carwyn Jones announced he would step down in the autumn will ultimately result in the project being scrapped.

A public inquiry into the scheme has concluded and is expected to report back in the coming months.

But, speaking following Mr Jones' shock announcement at the weekend, Mr Davies said: "The entire project could just get put on hold, and might even get put in the bin as one of the casualties of commitments various leadership runners make."

He added: "We will probably have to get to January or February next year before a new first minister is in a position after setting a new cabinet to do it for a decision to be made.

"It might be that the M4 relief road falls by the wayside. A new first minister might clearly state it will not be a priority for them to deliver an M4 relief road and they will look at other options."

And he quizzed Mr Jones during First Minister's Questions yesterday.

Mr Davies asked: "Can you confidently say that, with the intention you announced on Saturday, the M4 relief road will proceed on the basis of the support the government has given to date - namely, continuation of the support for the black route? As you have indicated that has been a personal goal for you to deliver, and now we know that there will be a new first minister, can you say that that will remain a Welsh Government priority?"

Saying "I don't think I've expressed a strong preference for either route", Mr Jones replied: "There is no doubt there's a problem.

"We can all see what the issue is in the tunnels at Brynglas, and that problem is not easy to resolve.

"I will consider the evidence of the planning inspector when I get that evidence."

Speaking outside the chamber, Mr Davies said: “It looks like the M4 relief road is going to be the first casualty of Labour’s leadership contest."

He added: “This is just the first major decision that will now be parked until a new leader is in place."

Finance secretary Mark Drakeford, who is so far the only person to officially announce they will stand to replace Mr Jones, said he would wait for the outcome of the enquiry before making a decision on the project.

"I do not think it would be sensible for anyone to say that, in coming in they would want to set aside all the work and the enormous amount of effort people have put into the public enquiry," he said.

He added: "It's just not sensible to parachute in over the top of such a detailed process in which so many people have been involved."