The expenses watchdog is looking into claims that an alleged “gay sex party” at the Conservative Party conference was partly paid for using public money.

According to The Independent newspaper, the Independent Parliamentary Standards Authority (IPSA) is “deeply concerned” by the claims.

The newspaper reports that concerns were raised with senior Tory officials at the 2011 Conservative Party conference, after members took to Grindr to advertise the sex party

The Policy Research Unit (PRU), which is paid to carry out research on behalf of MPs, is alleged to have been used to book the rooms at Manchester’s Light ApartHotel, where the party took place.

IPSA’s rules state that “attendance at political party conferences or meetings” cannot be covered by expenses, and that “staffing expenditure may not be claimed for any party political activity”.

Suites in the hotel can cost as much as £2,500 per night.

Ipsa said in a statement: “MPs who use a parliamentary research company, such as PRU, can seek reimbursement for the cost as a perfectly reasonable claim. Allegations that the PRU has misused public money are deeply worrying and pose serious questions for the PRU board to answer.

“We have received the proper assurances and evidence from all MPs who claim through PRU but, in the light of these concerns, we will be contacting PRU to seek further assurance about their work and that the claims fall within Ipsa’s scheme.”

Conservative MP Michael Fabricant went public at the weekend to denounce claims that he was in “a feud” with former PRU boss Iain Corby.

Mr Fabricant, sacked as Tory vice chairman last week, revealed he told party chiefs of concerns about the PRU’s “drinking culture” three years ago – but no action was taken.

In a statement he said: “There is no feud. In 2011, I met with two members of PRU staff, both of whom felt that activities in the PRU at the time fell far below the standards expected of a professional employer.

“One of them made the case that he is neither gay nor willing to involve himself in a culture of long drinking sessions.

“He believed he was not being treated fairly despite his annual reviews saying his work was outstanding. Others had received modest pay rises while he had not.

“He had even been told in front of a Minister that he was a “whip’s nark” or whistleblower. As a consequence he left for a better job. I reported this to the appropriate authorities and that was that.”