A top adviser to Jeremy Corbyn was suspended from his role at some point over the last few days.
David Prescott, who is political adviser to the Labour leader and the shadow cabinet, helps to write Mr Corbyn's speeches.
He is also believed to be part of the team that prepares Mr Corbyn to face Theresa May at Prime Minister's Questions.
When asked about the reasons for Mr Prescott's suspension, a Labour Party spokesperson said: "We don't comment on staffing matters."
Mr Prescott, who is the son of former deputy prime minister John Prescott, made an unsuccessful bid to be selected as Labour's candidate in Hull West and Hessle ahead of June's election.
He lost to Tory incumbent Sir Edward Leigh in Gainsborough as a parliamentary candidate at the 2015 election.
He also previously failed to be selected to stand for the party in his father's old Hull East seat ahead of the 2010 election, after which Mr Prescott senior was appointed to the House of Lords.
Mr Prescott joined Mr Corbyn's office in October last year, having spent six years at communications consultancy Commucan.
Prior to his appointment, Mr Prescott used a blog post to call for a "much sharper operation in Corbyn's office and an increased level of professionalism" from the Labour leader inside and outside Parliament.