Government plans to drastically scale up nuclear capacity are more of a “wish list”, with the role of Great British Nuclear still ambiguous, MPs have said.

Parliamentarians on the Science, Innovation and Technology Committee said questions remain for ministers’ ambitious nuclear goals, with doubts over whether the Government has a specific strategy to meet the target of bolstering the UK’s nuclear capacity to 24 gigawatts (GW) of electricity by 2050.

The new 118-page report, published on Monday, backs the Government’s decision to look to nuclear power as a way to meet the UK’s electricity needs amid the race to net zero.

It warns that the Government’s own most recent energy security plan, published in March, offers little clue about how measures will be implemented.

Current plans, MPs warn, do “not amount to the comprehensive, detailed and specific strategy that we believe is required if the Government’s aspirations are to be delivered”.

Greg Clark, chair of the Science, Innovation and Technology Committee, said: “The Government is right to identify nuclear power as an important contributor to meeting our future electricity needs. It has stretching ambitions to achieve 24GW of nuclear power by 2050.

“This would be almost double the highest level of nuclear generation that the UK has ever attained.

“The only way to achieve this is to translate these very high-level aspirations into a comprehensive, concrete and detailed nuclear strategic plan which is developed jointly with the nuclear industry, which enjoys long-term cross-party political commitment and which therefore offers dependability for private and public investment decisions.”

Elsewhere, the report also questions the exact purpose of Great British Nuclear (GBN), an arm’s-length body currently involved in the Government-backed competition to develop smaller-scale nuclear technology projects.

Earlier this month, Energy Secretary Grant Shapps hailed a “renaissance” in nuclear energy in the UK, with GBN playing a key role.

MPs said: “There is still ambiguity over what GBN’s exact remit will be in the future, beyond running a SMR (small modular reactor) competition.

“We recommend that the Government should set out a more comprehensive statement of GBN’s remit, operational model and budget, and its intended role with respect to ministers and government departments.”

Campaigners against the Sizewell C nuclear power plant project in Suffolk welcomed the committee’s call for Government clarity on the financing of gigawatt-scale nuclear projects.

MPs said “the choice to proceed with gigawatt-scale nuclear power should not be made without robust estimates of its value for money, including the financial value of the construction risk being assumed by taxpayers or billpayers”.

“A headline lower cost than Hinkley Point C is not justified if the value of the risk is too great. This is true even if it forces a conclusion that — for all its other advantages — gigawatt scale new nuclear is not financeable on defensible terms, and that the UK’s nuclear ambition would need to be pursued through other nuclear technologies,” the report found.

A spokesperson for the Stop Sizewell C campaign said: “We’re appalled that the committee has ignored legitimate concerns about whether nuclear can deliver reliable, affordable electricity.”

The group said it supported “the committee calling for the Government to publish Sizewell C’s cost and value for money, as doing so will expose just how unjustifiable this slow, risky, expensive project is”.

A Department for Energy Security and Net Zero spokesperson said: “We have already made clear we will publish a nuclear roadmap and consult on alternative routes to market by the end of the year.

“Nuclear has a vital role to play in reaching net zero and boosting energy security – just last week we launched Great British Nuclear which will help generate billions for the UK economy and support thousands of jobs.”