Boris Johnson has broken rules governing how soon ex-ministers can take new jobs in the private sector after leaving office.
The former foreign secretary failed to apply for permission from the ministerial watchdog to accept his role writing a column for The Daily Telegraph.
Mr Johnson – who was being paid £275,000 for his columns by the paper before becoming a minister – had his first article since resigning published this week, despite rules saying he should have waited three months.
But as the watchdog Acoba (Advisory Committee on Business Appointments) is unable to take serious action, critics called for a new tougher system to govern post-ministerial appointments.
Layla Moran, Lib Dem MP and representative of the anti-Brexit group Best for Britain, said: “The worst Boris faces for this disgraceful behaviour is just a slap on the wrist.”
She added: “For once he should pay the price for his actions.”
Labour’s shadow minister for the Cabinet Office, Jon Trickett, also called for a “radical overhaul” of the system, in light of Mr Johnson’s actions.
Under the rules, ministers must notify and gain the consent of Acoba before taking up new positions after leaving office, with a three-month ban in place.
The rules are designed to stop ministers using their knowledge of current operations to make profit in the private sector.
A spokesman for Acoba said Mr Johnson had not sought its advice before returning to the role.
Despite breaking the rules, it is likely Mr Johnson will get away with little more than a slap on the wrist, given the watchdog does not have strong powers to sanction politicians who do not follow its advice.
An influential committee of MPs branded Acoba part of an “ineffectual system for regulating the ‘revolving door’ between the public and private sector” in a report in January.
The Public Administration and Constitutional Affairs Committee went on to attack the government for not taking the matter seriously, adding: “The failures of governments in this regard have damaged public trust in politics and public institutions, and led to repeated scandals.”