Rishi Sunak has taken up paid adviser roles at tech giant Microsoft and artificial intelligence start-up Anthropic.

The former prime minister has been told he must not lobby ministers on behalf of the companies by the Advisory Committee on Business Appointments (Acoba), an independent watchdog which oversees the activities of former government figures.

Sunak - who remains the MP for Richmond and Northallerton - said he was "delighted" to be working "with two of the world's leading tech firms" and planned to donate his earnings to a charity he founded.

During his premiership, Sunak made tech regulation a significant priority, setting up an AI safety summit in 2023.

In letters of advice sent to Sunak by Acoba and published on Thursday, his part-time role at Microsoft was described as providing "high-level strategic perspectives" on geopolitical trends.

The watchdog said it had been informed by Sunak that his part-time advisory role at Anthropic - an AI firm seeking to compete with companies like OpenAI, Google and Meta - would be "akin to operating as an internal think tank".

Acoba said Anthropic "has a significant interest in UK government policy", meaning that Sunak's appointment could potentially be seen to offer "unfair access and influence" within government.

The appointment with Microsoft, a "major investor" in the UK, also presented similar issues, it wrote.

However, it also said that his time spent out of government would have reduced the value of any information Sunak may still possess, while reiterating the standing rules ex-ministers have to abide when seeking employment after leaving government.

Sunak was told not to advise on bidding for UK contracts, or to lobby the government for two years from his last day in ministerial office.

In addition to the two tech roles, it was previously confirmed Sunak will act as a paid advisor to the bank Goldman Sachs, where he previously worked between 2001 and 2004.

There had been speculation that Sunak, who was in No 10 between October 2022 and July 2024, would leave the Commons to take up a Silicon Valley role shortly after the election.

He previously lived in California, where he still has a home, and held a US visa until 2021.

But in his final prime minister's questions, Sunak vowed to spend more time in his constituency, which he called "the greatest place on Earth".

"If anyone needs me, I will be in Yorkshire," he said.

All proceeds from the new roles will be donated to The Richmond Project, a charity Sunak founded with his wife to tackle numeracy problems in the UK, another area he was vocal about while in Downing Street.

Posting on social media, Sunak said he would use his roles to "ensure" that the coming technological change "delivers the improvements in all of our lives".

Sunak said: "I have long believed that technology will transform our world and play a key part in determining our future.

"We stand on the edge of a technological revolution whose impacts will be as profound as those of the industrial revolution, and felt more quickly."