The founder of a tech group at which former prime minister David Cameron was an adviser has stepped down amid allegations of sexual harassment.

Zia Chishti, who founded Afiniti, was accused this week of pressuring a former employee into having sex with him on a business trip, when it was also alleged he beat her.

In a brief statement from the firm’s Bermuda head office, the company said: “The board of directors of Afiniti announces that Mr Zia Chishti has stepped down from his role as chairman, chief executive officer, and director of Afiniti, effective immediately.”

The allegations were made by Tatiana Spottiswoode, a law student at Columbia Law School, during a hearing in front of the US Congress on Tuesday.

Mr Cameron announced his resignation as chairman of the advisory board to Afiniti shortly afterwards.

A spokesman for the former PM said: “The alleged events took place before David Cameron started working for Afiniti and he had absolutely no knowledge of them until just before (the) congressional hearing.”

Ms Spottiswoode told the hearing that after signing a contract with the company in April 2016, it became clear Mr Chisti “was not willing to treat me like an employee”.

“Instead, over the next 18 months he oscillated between pressuring me for sex and punishing me,” she said.

“When I rebuffed him he humiliated me in front of co-workers and then ignored me completely, causing me to fear for my job.”

Mr Cameron’s post-political career after leaving Downing Street in 2016 has been tarnished by the Greensill affair.

Multiple inquiries were launched after he was widely criticised for privately lobbying ministers in an attempt to secure access to an emergency coronavirus loan scheme for the firm, which collapsed in March.

Investors in Afiniti, which also employs Princess Beatrice in its New York offices, have called for an investigation.

Swiss fund manager GAM, which has a 3% stake, called for an independent review into the allegations.

Afiniti provides call centre technology to companies including Virgin Media and Sky and was set up in 2005.

It has grown rapidly with rumours of a multibillion-pound stock market listing next year.