Welsh Secretary Alun Cairns has said he remains “supportive” of plans for a tidal lagoon in Swansea Bay but warned it must be value for money.
It follows a question from Plaid Cymru’s parliamentary leader Liz Saville Roberts amid concern about delays to the £1.3bn scheme.
Mr Cairns said he had discussed it with Department for Business, Energy and Industrial Strategy ministers.
There has been concern investors might withdraw if it is not approved shortly.
In March 2015, the then chancellor George Osborne announced in his Budget speech that commercial negotiations had begun, with the main focus on how much extra customers should pay to subsidise the project.
In January, an independent report by former energy minister Charles Hendry said tidal lagoons were cost effective and would make a “strong contribution” to the UK’s energy supply.
It said moving ahead with a “pathfinder” project in Swansea Bay should be seen as a “no regrets” policy, but ministers have yet to give it the green light.
In a written parliamentary reply, Mr Cairns told Ms Saville Roberts: “I remain supportive of a tidal lagoon at Swansea Bay. Nevertheless, it is essential that we ensure the project represents value for money.”