The architect of the UK government’s AI strategy has joined the US startup Anthropic in a senior role a year after stepping down from his Downing Street post.

Matt Clifford, a successful tech investor, was appointed as AI opportunities adviser by Keir Starmer last year but resigned from the unpaid role six months later for personal reasons.

His move to the company behind the Claude chatbot has raised concern, with the head of the House of Commons science, innovation and technology committee, Chi Onwurah, saying that his decision to remain as chair of the government-backed Aria funding body represented a “clear conflict of interest”.

Clifford will be Anthropic’s managing director, international affairs, and will lead the company’s engagement with governments outside the US including in the UK, Europe, Asia-Pacific and India.

Anthropic said Clifford would remain as the chair of Aria, the UK’s Advanced Research and Invention Agency, which funds “moonshot” science and tech projects. He will also maintain his chair role at Entrepreneurs First, the tech venture capital firm he co-founded.

He was appointed chair of Aria in 2022. Anthropic said Clifford would step back from any matter involving the company at Aria. But Onwurah said the roles clashed and she called on the AI minister, Kanishka Narayan, to intervene.

“His intention to remain as chair of Aria, which spends taxpayer money on cutting-edge research, much of it related to or driven by AI, is a clear conflict of interest and I look forward to the AI minister setting out clear boundaries,” Onwurah said.

Anthropic said its commercial relationship with Aria was handled by a separate team to Clifford’s and he did not make procurement or programme-level spending decision at Aria anyway.

“Matt has no involvement in any decision touching Anthropic, and that arrangement has been agreed with Aria and the Department of Business, Innovation, Science and Trade, which is responsible for appointing Aria’s chair,” the company said.

The UK government has been approached for comment.

Several senior politicians have taken roles at Silicon Valley firms in recent years. The former deputy prime minister Nick Clegg took a senior post at Meta in 2018. Last year the former prime minister Rishi Sunak took advisory roles at Microsoft and Anthropic, and the ex-chancellor George Osborne joined OpenAI.

Commenting on his role at Anthropic, Clifford said the most important decisions about AI would be made by companies and governments together. He said: “Countries everywhere want real agency over how this technology is built and used, and my job is to make Anthropic a genuine partner in that – in Europe, Asia and beyond.”

Anthropic is preparing for a stock exchange flotation that could value the business at $2tn (£1.5tn).

Tom Brake, the chief executive of Unlock Democracy, a not-for-profit campaign group, said the move showed that “the revolving door is a problem for advisers as much as it is for ministers”.

“Taking extensive knowledge obtained within government, about a policy as sensitive as AI, to a private sector company shortly after leaving government gives that company a huge advantage,” said Brake, a Liberal Democrat MP from 1997 to 2019. “Regardless of any safeguards, this weakens the government’s hand when pushing for a precautionary approach towards AI development.”

Beeban Kidron, a crossbench peer and prominent critic of the government’s AI policy, said: “We need more independent politics which puts the interests of workers, citizens and society at the forefront of our relationship with the tech sector.”

An Anthropic spokesperson said the UK was “one of dozens” of governments Clifford’s team would engage with. “We hire people with expertise and who understand how government works because our work requires it – in every market, not just the UK,” they said.

Clifford began his tech career in the private sector. Prior to his government work, he was an established figure on the UK tech scene as a co-founder of Entrepreneurs First, which has helped build tech companies with a combined worth of more than $20bn.

Clifford worked with Sunak’s government as his representative to the 2023 AI Safety Summit in the UK, and helped create the organisation that later became the world-leading AI Security Institute.

He was appointed as Starmer’s AI adviser after drafting the government’s AI action plan, which supports the creation of AI growth zones to host datacentres and the building of the UK’s own AI models.