Claims a Jeremy Corbyn aide has been working in his Commons office without security clearance are being investigated by the parliamentary authorities.
Iram Awan, the Labour leader’s private secretary, was reported by the Huffington Post to be routinely working in Parliament on a visitor pass.
The Commons authorities say this is against the rules.
Labour said it did not comment on “staffing matters”.
The Huffington Post claims Ms Awan has for nine months been escorted to Mr Corbyn’s Commons office by other members of his team, who do have security clearance.
This means she will have passed through airport-style X-ray machines and security checks, like other visitors to the parliamentary estate.
A Labour source said: “We have not been told that any members of staff have been refused a pass or any reasons for why any pass may not have been granted.”
A Commons spokesman said: “Visitor passes are for visitors only. They cannot be used to carry out work on the parliamentary estate.”
The spokesman said they could not comment on individual cases but added an “investigation into an alleged breach of the Parliamentary rules has been launched”.
The investigation is reported to have been launched after Conservative MP Leo Docherty wrote to the serjeant at arms, Kamal El-Hajji, who is in charge of security at the House of Commons, to request one.