Labour has been accused of breaking another promise after GB energy chairman Jurgen Maier admitted it could take 20 years for the investment vehicle to create 1,000 jobs.

The promised jobs bonanza was part of a Labour’s general election campaign, but there has been a reluctance by ministers to put a time frame on its plans.

Sir Keir Starmer said Labour would fund GB Energy’s renewables investments with £8 billion raised mainly from the windfall taxes on oil and gas company profits. The organisation will be based in yet-to-be identified offices in Aberdeen, with satellite offices in Glasgow and Edinburgh.

During an appearance before MPs at Westminster in October, Mr Maier suggested more than 1,000 jobs could be created in the northeast of Scotland. He has now admitted in a television interview that “in the very long term, as we become a major energy champion it may be many more [jobs] than that.”

Asked if it could take 20 years to get to 1,000 jobs, he said: “Absolutely.”

Mr Maier, a former chief executive of Siemens UK, could not give a fixed date on when energy bills would be cut by up to £300 as a result of the company’s activities, which was also promised by Labour.

SNP Westminster Leader Stephen Flynn said it was “yet another broken promise from Keir Starmer” and challenged the Prime Minister to “come clean over why he is failing to deliver the promises he made at the election – and admit whether these pledges are being kicked into the long grass.”

The Aberdeen South MP warned the UK government is “failing” to deliver the scale of investment needed to maximise Scotland’s potential as a “renewable energy powerhouse” – and pointed to the fact that the Chancellor’s economy speech failed to announce any new investment for Scotland.

Scottish Conservative shadow energy and net zero secretary Douglas Lumsden said: “This jaw-dropping admission confirms that Labour’s flagship GB Energy project is nothing more than a gimmick.

“Sir Keir Starmer promised the North East that this was the magic bullet to create jobs and cut energy bills, but those plans are spectacularly unravelling.

“The fact that it will take two decades for GB Energy to deliver 1,000 jobs in Aberdeen is a hammer blow for the region at a time when Labour and the SNP have already shamefully turned their backs on the oil and gas sector.

“Out-of-touch left-wing politicians must accept that their current approach to our energy needs is simply not working and change tack. They must adopt our common sense plans and accept we will need to use our own oil and gas for years to come, rather than suddenly turning off the taps.

“If they don’t, tens of thousands of highly skilled jobs as well as our energy security will be hugely threatened and it is clearer than ever that GB Energy will not deliver anywhere near the change what Labour promised.”