Boris Johnson has proposed banning MPs from acting as paid political consultants or lobbyists as he tries to stem the sleaze row that has battered the Tory party.

The Prime Minister also called for the Commons Code of Conduct to be updated and for MPs who fail to focus on their constituents to be “investigated and appropriately punished”.

Mr Johnson outlined the plans as Labour Leader Sir Keir Starmer was due to detail his bid to force a potentially damaging vote for the Government on taking action to tackle sleaze.

Detailing his plans in a letter to Commons Speaker Sir Lindsay Hoyle, the Prime Minister said they would ensure MPs who are “neglecting their duties to their constituents and prioritising outside interests would be investigated, and appropriately punished by the existing disciplinary authorities”.

“They would also ban MPs from exploiting their positions by acting as paid political consultants or lobbyists,” Mr Johnson added.

The move is an attempt to draw a line under the damaging saga that began with Mr Johnson’s bid to overhaul the disciplinary system to prevent the immediate suspension of Owen Paterson.

The Prime Minister was forced to U-turn on that plan and the Conservative former minister resigned as the MP for North Shropshire as a vote was rescheduled to ban him from the Commons for six weeks for breaching lobbying rules.

Mr Johnson’s latest plans came a day ahead of Labour staging a vote to ban MPs from taking paid consultancies or directorships during an opposition day debate on Wednesday.

The Government and Conservative backbenchers would have found themselves in the difficult position of having to either back Labour’s plans or face allegations they were not stamping out sleaze.

Mr Johnson sent Sir Lindsay two key recommendations from the Committee on Standards in Public Life’s report on MPs outside interests from 2018.

These included changing their code of conduct so that any outside work should be “within reasonable limits” and “not prevent them from fully carrying out” their duties.

The rules would also ban MPs from accepting paid work as a parliamentary strategist, adviser or consultant, and from accepting payment or offers of employment to act as political consultants.

Mr Johnson said changing the Commons code is “rightly a matter for Parliament” but said he believes those two recommendations would be the basis of a “viable approach which could command the confidence of parliamentarians and the public”.