Ministers’ hopes of getting Britain’s new “moonshot” scientific research agency off to a flying start have been dealt a blow by the withdrawal of the boss appointed to lead it just six weeks ago.

Sky News has learnt that Dr Peter Highnam, deputy director of the US Defense Advanced Research Projects Agency (DARPA), has decided not to take up the chief executive’s post at the Advanced Research and Invention Agency (ARIA).

Sources said on Thursday that Dr Highnam’s decision had been taken for personal reasons and that he was still likely to undertake advisory work for ARIA on an ongoing basis.

The government is now expected to resume sifting through its previous shortlist of candidates to become ARIA’s inaugural chief executive, they added.

Dr Highnam’s appointment, which was announced at the beginning of February, was hailed by Kwasi Kwarteng, the business secretary, as “a major triumph for the UK”.

“His expert direction will lead the agency’s formation, ensuring the funding of high-risk programmes that will continue to push the boundaries of science and technology,” Mr Kwarteng said at the time.

“Under Dr Highnam’s leadership, ARIA will ensure the benefits of research and development will be felt in our society and economy over the course of generations, and that the technologies, discoveries, products, and ideas the agency invests in are supported to create the industries of tomorrow.”

Britain’s new “high risk, high reward” inventions agency, as it has been dubbed, will have an initial budget of £800m, and is aimed at helping the UK “maintain its position as a global science superpower”, according to an announcement from the government about its establishment last year.

The Department for Business, Energy and Industrial Strategy (BEIS) said last February that ARIA would have “a much higher tolerance for failure than is normal, recognising that in research the freedom to fail is often also the freedom to succeed”.

ARIA’s mandate will be to focus on “moonshot” projects spearheaded by “inspiring inventors”, BEIS added.

The new agency was the brainchild of Dominic Cummings, Boris Johnson’s former top adviser who left Downing Street in acrimonious circumstances last year and who has continued to be a thorn in the prime minister’s side as pressure on him has grown in recent months.

The Department for Business, Energy and Industrial Strategy has been contacted for comment.