Ministers who leave office following a “serious breach” of ministerial rules will be stopped from getting pay-outs from October.

The move is part of a package of measures the government says will drive up standards in politics.

Meanwhile, former ministers who take up a job which breaches post-government employment rules will also be asked to repay any severance payment.

As part of the shake-up, the existing watchdog, which has been criticised as “toothless”, will be scrapped.

The functions of the Advisory Committee for Business Appointments (Acoba), which vets jobs taken up by former ministers and senior officials to avoid conflicts of interest, will be split between existing bodies.

A new Ethics and Integrity Commission will also be established by reforming the Committee on Standards in Public Life, which advises the prime minister, with new powers to strip former ministers of exit payments.

It will be chaired by Lt Gen Doug Chalmers, a former military chief who currently chairs the committee.

Currently ministers are entitled to a severance payment equivalent to three months’ salary when they leave office for any reason, regardless of how long they have been in the job.

This has led to outrage over payments worth thousands of pounds for ministers who were in the job for just a few weeks, including during Liz Truss’s short-lived premiership.

Under the changes, which will come into effect from 13 October, ministers who leave office having served fewer than six months, or following a “serious” breach of the Ministerial Code, will no longer get the payment.

Ministers who return to office within three months of leaving will also forgo their salary until the end of that three-month period.

Meanwhile, the system for vetting post-government jobs is being strengthened so former ministers face a financial penalty if they seriously breach the rules, and will be asked to repay any severance payment.

The rules apply to ministers, civil servants and special advisers for either one or two years after they leave their role, depending on their seniority.

Currently ministers must seek advice from Acoba about any job they wish to take up within two years of leaving office, a period during which they are also not allowed to lobby the government.

Advice from the committee can range from delaying taking up the role, not taking part in certain activities, or not taking the job at all.

However, Acoba has no way of forcing people to comply with its advice and cannot sanction former ministers.

High-profile examples of this include Boris Johnson, who has been found by Acoba to have breached its rules by not seeking advice from the watchdog before taking up columnist roles, but faced no penalty.

The Liberal Democrats welcomed the plans as “the right step after years of Conservative sleaze which did so much damage to standards in public life”.

“Its lack of powers to enforce the rules it oversaw meant Acoba was about as useful as a chocolate teapot,” a spokesperson said.

“It shouldn’t have taken a year to set up the Ethics and Integrity Commission – and there will be no excuse if the government attempts to kick these vital issues into the long grass,” the spokesperson added.

Labour has long promised to strengthen the rules on post-government jobs and lobbying, with the pledge included in the party’s election manifesto.

Conservative shadow minister Alex Burghart said the announcement amounted to “cosmetic re-brands of existing bodies”.

Cabinet Office Minister Pat McFadden said: “This overhaul will mean there are stronger rules, fewer quangos and clearer lines of accountability.”

He added: “But whatever the institutional landscape, the public will in the end judge politicians and government by how they do their jobs and how they fulfil the principles of public service.”