Boris Johnson could face sanctions after failing to notify parliamentary authorities that he was returning to his job at The Daily Telegraph.
Mr Johnson went back to his role as a columnist on the newspaper after quitting Theresa May’s cabinet, a job he had held before the appointment to foreign secretary.
But Mr Johnson did not tell the Advisory Committee on Business Appointments (Acoba) that he intended to write for The Telegraph again, and may face sanctions.
Under the ministerial code, cabinet ministers should seek advice from Acoba before taking a new role after they leave cabinet.
They are required to wait three months before taking an outside role.
Jon Trickett MP, Labour’s shadow minister for the cabinet office said: “Boris Johnson jumping straight from his role as a Government Minister to a job as a columnist makes a mockery of Acoba. If it was in any way a functioning body, this kind of thing would be blocked.
“People are sick and tired of the political establishment’s revolving door, which sees a closely-knit clique move from government into cushy new jobs.
“Acoba hasn’t got the teeth to stop this behaviour. We urgently need a radical overhaul of the system.”
Mr Johnson and the cabinet office have been contacted for comment by Sky News.