More uncertainty surrounds GB Energy, one of Labour’s flagship election pledges, despite the Treasury insisting it is committed to fully funding the project.

It was reported on Friday that the Treasury was weighing up whether to cut £3.3 billion of the £8.3 bn allocated to the renewables investment vehicle as part of the Chancellor’s anticipated spending clampdown.

Labour sources say the Treasury has been told that cuts to the controversial state-owned company would cost votes in the Scottish elections next year.

It is being set up to steer investment in major developments that might otherwise struggle for funding, though this has raised questions about a conflict of interest.

GB Energy is supposed to play a key role in reducing energy bills but plans to invest in schemes such as floating offshore wind turbines is expensive.

It is due to draw down funds raised from the windfall tax, or energy profits levy, on oil and gas firms, but pressure is mounting on ministers to reform the tax or wind it down sooner than its 2030 deadline as more North Sea companies announce job cuts.

Crucially, profits that were due to be directed to investing in clean technologies are being wiped out. Harbour Energy, a major North Sea player, was the latest last week to report that its annual profit had turned to a loss as a result of the levy.

Opposition parties warn that this shows the damage being caused in the race to net zero and that GB Energy will need to move quickly and decisively if it is to convince sceptics that it is nothing more than a vanity project.

Earlier projections billed GB Energy as a state-owned electricity generator that would help cut bills by £300, a claim repeated by Scottish Labour leader Anas Sarwar in the election campaign. It is now promoted as a vehicle for aiding investment, and the cut in bills seems a long way off.

In a radio interview on Friday, Scottish Secretary Ian Murray struggled to answer questions on when bills would come down.

Energy sources say Labour has erred by giving the impression that bills would be cut within weeks of coming to power when the reality is that they will fall over the course of the parliament – and beyond – once the UK becomes less reliant on wholesale gas prices. Even that claim is challenged, given the degree to which the UK relies, and will continue to rely, on gas.

However, there are promises from industry that electricity prices will begin to come down steeply once grid capacity is increased and battery storage is at a more advanced stage.

Zenobe, whose battery storage plant in the north of Scotland has just gone live, said it would “significantly reduce the amount of wasted clean energy” and estimates that it will lower consumer bills by more than £170 over 15 years.

So far, the government has spent £25m in set-up costs for GB Energy and a further £100m has been set aside in capital over the next financial year.

Its chairman Jürgen Maier, a former Siemens boss, came in for criticism after stating that the promise of 1,000 jobs could take 20 years. Ian Murray yesterday said this figure includes jobs that GB Energy will create rather than those it will employ directly.

“It’s not about how many people work in the GB Energy HQ. It’s about how many jobs it creates in terms of the renewables industry,” said Mr Murray.

In what looked like another move to head off criticism, ministers installed Daniel McGrail, the former chief executive of RenewableUK, as interim chief executive on the opening day of the Scottish Labour party conference.

There was some criticism that Mr Maier will not be based in Aberdeen and that GB Energy will not have a standalone HQ, though this is not unusual practice for non-executive directors and many organisations share offices.