A Tory MP quizzed by police over reports of drunken groping in a parliamentary bar was “holding on to bottoms in a bid not to fall on the floor”, it has been claimed.

Ross Thomson, MP for Aberdeen South, is thought to have been drinking for at least five hours before the incident on Tuesday. He was seen in a House of Commons bar at about 6pm, before officers were called to another Westminster watering hole, Strangers’ Bar, just after 11pm.

The Metropolitan Police said in a statement on Wednesday that the officers were responding to “a report of sexual touching". "Officers attended and spoke to the parties involved - three men in their 20s and 30s. However, no formal allegations were made to the officers and no arrests were made,” the statement continued.

Shortly before police were called, “a government minister tried to persuade Thomson, who witnesses described as being incredibly drunk, to go to home”, The Times reports.

Lord Duncan of Springbank, a Scotland Office minister, and David Duguid, a fellow Scottish Tory MP, tried to convince the 31-year-old to leave. “It is understood that Thomson did leave the bar a number of times but kept returning,” adds the newspaper.

Witnesses told The Times that Thomson could barely stand and that fellow drinkers feared he might vomit over them. “He was handsy, yes, and holding people all over, but it was in a bid to stand upright,” a source said. Thomson was “holding on to bottoms, but in a bid not to fall on the floor”, the witness added.

The Daily Telegraph reports that the Scottish Conservatives are aware of the claims and have launched an investigation.

Speaking at the Scottish Parliament on Thursday, deputy leader Jackson Carlaw said he had been made aware of the incident through social media.

“Inquiries are ongoing, however I know enough to say that the alleged behaviour is completely unacceptable and falls well below the standard I think any of us would expect of any elected representative”, Carlaw said.

Tory party insiders “are understood to be very concerned about Thomson’s welfare”, says The Times.

The Guardian says the incident “follows a concerted bid by the authorities to clamp down on a late-night drinking culture in Parliament”.

Thomson is yet to make a statement about the incident.