David Prescott, the son of former deputy prime minister and Hull East MP John Prescott, has been suspended from his job in Jeremy Corbyn's office.
Mr Prescott is understood to have been suspended under standard employment practices after allegations were received by the Labour leader's office.
The claims are believed to have come to light following recent reporting of alleged misconduct at Westminster.
Labour has so far refused to comment on the story.
Mr Prescott has emerged as a key member of Mr Corbyn's team, working as communications manager to the shadow cabinet, having previously been brought in as a speechwriter.
He stood as Labour's candidate in Gainsborough in the 2015 election, but lost to Conservative incumbent Sir Edward Leigh.
Earlier this year, he failed to gain the nomination as the party's candidate in Hull West and Hessle after former home secretary Alan Johnson announced he was standing down in June's election.