New ministerial code cracks down on bullying and harassment
Ministers can be sacked for bullying, harassment or "inappropriate or discriminating behaviour" under a code of conduct published by Theresa May.
The updated ministerial code also says ministers must report official meetings in the UK or overseas.
If follows a string of scandals which claimed the scalps of former cabinet members Damian Green, Sir Michael Fallon and Priti Patel.
Theresa May has ordered her ministers to read the revamped document.
The ministerial code of conduct was introduced by John Major in 1992 and has gone through several updates, usually in response to scandals. The last version was published by Mrs May in December 2016.
Since then, Sir Michael Fallon has quit as defence secretary after allegations of improper advances towards female journalists.
Last month Mr Green was asked to quit as First Secretary of State after he was judged to have breached the ministerial code by making "inaccurate and misleading" statements over what he knew about claims pornography was found on his office computer in 2008.
Independent complaints system
The new code spells out, for the first time, that "harassing, bullying or other inappropriate or discriminating behaviour wherever it takes place is not consistent with the Ministerial Code and will not be tolerated".
Ms Patel resigned as international development secretary in November after failing to report meetings with Israeli government officials during a private holiday in the country.
The incident has led to a new section in the ministerial code, which says: "If a minister meets an external organisation or individual and finds themselves discussing official business without an official present - for example at a social occasion or on holiday - any significant content should be passed back to the department as soon as possible after the event".
Ministers can continue to sit as MPs if they have been fired from the cabinet or other departmental job and the new rules do not apply to backbenchers or members of opposition parties.
Several Conservative and Labour MPs are still under investigation following allegations about their behaviour.
Commons leader Andrea Leadsom is drawing up plans with a cross-party working group for an independent complaints system to tackle abuse and harassment in Parliament.
Mrs May announced the publication of the new code for ministers at the first meeting of her newly reshuffled cabinet in 10 Downing Street.
The prime minister "asked all cabinet colleagues to confirm at a later date that they and their ministerial teams have read it", her official spokesman said.