Politicians should face legal action if they fall foul of the rules by abusing the “revolving door” between Government and private sector jobs, MPs said.

The terms governing ministers’ employment prospects on leaving their Whitehall roles should be expanded to act as a “sufficient deterrent” to improper conduct, as part of a drive to safeguard the “integrity” of public life, according to a parliamentary committee.

The MPs are also calling for the Government’s ethics watchdogs to be given legal status, as they warned the Home Secretary’s resurrection in her Cabinet role just days after she was forced out for a security breach set a “dangerous precedent” for the enforcement of the ministerial code.

In a new report, the Public Administration and Constitutional Affairs Committee (PACAC) has made a series of recommendations to toughen Whitehall’s standards and ethics system in the wake of “damaging” scandals such as the Greensill and Partygate rows.

These include an expansion of the business appointment rules, which are enshrined in the ministerial and Civil Service management codes and determine which jobs ministers and senior officials can take up after leaving office.

As it stands, these politicians and civil servants must apply to the Advisory Committee on Business Appointments (Acoba) before accepting any employment for two years following their exit, and are banned from lobbying Government for the same period.

But rare rule-breaking currently attracts “only negative publicity at worst”, the MPs warned.

In 2018, Boris Johnson was sharply criticised following his resignation as foreign secretary for resuming his column with The Daily Telegraph without clearing it with Acoba.

There have since been calls for the rules to be tightened in the wake of former prime minister David Cameron’s involvement in lobbying ministers and officials on behalf of the failed finance company Greensill Capital.

Mr Cameron’s actions were deemed permissible as he only became involved with the firm after he had been out of Government for more than two years.

By making the business appointment rules legally enforceable, the MPs said breaches could be pursued through the courts.

The PACAC said it has been told ministers are exploring “contractual mechanisms” to this end, and called for more detail on the form this will take and the sanctions that will apply, as well as a timeline for implementation.

The MPs also want a greater role for select committees, including endorsing appointments for the chairmen and women of ethics watchdogs, and requiring a minister to provide an explanation in a public hearing if they choose to ignore the advice of a recruitment panel.

PACAC chairman William Wragg said: “It is incumbent on the Government to ensure a robust and effective system for upholding standards in public life is put in place, with proper sanctions for those who break the rules.

“Our inquiry has found that, although we have a sophisticated landscape of ethics watchdogs in the UK to safeguard standards in public life, they lack the power to enforce the rules.

“The Prime Minister is rightly the ultimate arbiter of the rules in our system. We urge him to show leadership and give legal status to all the ethics watchdogs. This will provide a better deterrent for those who may be tempted to act improperly, and further safeguard the integrity of our public life.”

A Cabinet Office spokesman said: “We thank the committee for their report.

“We have been clear that this Government will have integrity, professionalism and accountability at every level and we are already taking action to improve the effectiveness of the business appointment rules.

“We will respond to the committee’s recommendations in due course.”