Plans to build Swansea’s pathfinder tidal power project face “genuine challenges”, according to Wales’ first minister, who has emerged in recent months as the project’s key champion.

Quizzed in the House of Commons on the project yesterday (13 March) during Business, Energy and Industrial Strategy (BEIS) ministers’ question time, the departmental secretary of state Greg Clark said he did not want to “close the door” on the wave project.

He said BEIS officials had been in Cardiff last week to discuss the lagoon with the Welsh government, which revived hopes for the project in January following an offer of direct financial support.

To underline the difficult choice that the UK government faces on the project, Clark quoted from a letter he had seen on the previous day from Carywn Jones in which the Welsh government’s first minister had acknowledged the “genuine challenges in…considering a proposal involving untried technology with high capital costs and significant uncertainties.”

Jones had written to the prime minister Theresa May in the run up to yesterday’s Spring Statement to emphasise the Welsh government’s support for the project.

Clark said: “The best way to do this is to explore all the possibilities and to recognise the constraints.

“We are in discussions with our colleagues in the Welsh government. I do not want to close the door on something if it is possible to find a way to justify it as being affordable to consumers.”

Jessica Morden, Labour MP for Newport East, said: “A decision on the Swansea Bay tidal lagoon is important for Wales as a whole. There is huge potential for future lagoons around Newport following the Swansea pathfinder. It is really important that we do not pass up these opportunities.”

The Swansea tidal lagoon project was recommended for approval last year in a report submitted to BEIS by former energy minister Charles Hendry.

Utility Week reported last month that the Welsh government’s offer of financial support could put the cost of generating electricity at the Swansea tidal lagoon on a par with the guaranteed strike price agreed for Hinkley C.

A Welsh government spokesperson, said: “Ahead of the Spring Statement, the first minister once again wrote to the prime minister reiterating the Welsh government’s strong support for the development of tidal energy. The letter made clear that we are prepared to consider a substantial investment to enable the Swansea project to move forward.

“As the secretary of state for Business, Energy and Industrial Strategy said in his recent letter to the first minister, we are considering a proposal involving untried technology with high capital costs and significant uncertainties. However, we believe the potential prize of a new tidal industry in the UK is great.”