Welsh First Minister Carwyn Jones has committed to providing further "substantial" investment to kick-start the world's first tidal lagoon energy scheme.
The First Minister has called on the UK Government to give the go-ahead to the £1.3 billion clean power project in Swansea Bay, which he said would create thousands of jobs and make Britain a world leader in a new industry.
The move comes a year after a review for the Government said lagoons to use the power of the tides to generate electricity could play a "cost-effective" role in the energy mix, help with security of supply, cut carbon emissions and bring opportunities for the UK supply chain.
Conducting the review, former energy minister Charles Hendry called on the Government to move ahead with a "pathfinder" lagoon project, to build on work already done for a scheme in Swansea Bay whose bid for subsidies prompted the review.
But the Government has failed to give the green light for the tidal lagoon, amid concerns about the costs of backing the renewable energy project.
In a recent letter to Prime Minister Theresa May, Mr Jones said the planned lagoon had "cross-party support" from Welsh MPs and Assembly members.
He offered a substantial equity or loan investment to reduce the cost of capital for the project.
He said: "This would be the world's first tidal lagoon power plant, which would create thousands of high quality jobs, open the prospect of meeting a significant proportion of the UK's energy needs from the tides and position Britain as a world leader in a new global industry.
"And yet the UK has been dragging its heels for over a year.
"This is leading to a growing sense of frustration among the Welsh business community and an increasing risk that the lack of a decision will turn into a decision not to proceed."
He urged the Government to "stop stalling" and get on with agreeing a guaranteed price for electricity generated by the lagoon so that it could go ahead.
Mark Shorrock, chief executive at Tidal Lagoon (Swansea Bay) Plc, the company behind the scheme, described the First Minister's commitment as "the breakthrough our project has needed".
He said: "We look forward to working alongside the Welsh Government to now close the deal for Swansea Bay Tidal Lagoon with the UK Government."
Welsh Conservatives called for more details on the commitment by Carwyn Jones, but backed his calls for the tidal lagoon to get the go-ahead.