The Ministry of Housing, Communities and Local Government has launched an investigation after it was revealed the diary secretary to housing minister Dominic Raab has been accused of selling sex online, raising security fears.
The civil servant is reported to have advertised on controversial website Seeking Arrangement, which describes itself as "the leading Sugar Daddy dating site".
She met twice with an undercover reporter for The Mirror posing as a wealthy businessman. She allegedly offered "full undisputed access" for £750 and boasted of her own knowledge of Raab's movements, saying: "I know everything about him. I know his every move. I know where he is today."
Civil servants are prevented by the Official Secrets Act from revealing sensitive or confidential information gained through their job.
There is no suggestion that Raab was aware of his aide’s actions.
According to the paper, the aide, who has not been named, admitted that her bosses at the department would “have an issue” with her extra work, but said: “I don’t care.”
A spokesperson for the department said: "We are aware of this allegation against one of our members of staff, and are investigating.
"There is no suggestion that any official information has been disclosed."
Former Scotland Yard royal protection chief Dai Davies warned the paper: "This revelation should cause grave concerns for those responsible for protection of our most senior politicians. This individual knows a great deal of sensitive information yet she does not even know who she is revealing it to.
"If she is being so open with someone she has barely met, then she could be liable to blackmail."