The possibility Boris Johnson could stay on as a “caretaker” prime minister until the autumn after he resigns today has caused concerns among government and opposition leaders.

The cabinet is split over whether Mr Johnson should stay or not until a new Conservative leader is appointed in October, sources close to the government have told Sky News.

Downing Street announced on Thursday morning the PM has agreed to stand down after an avalanche of resignations, with a new Tory leader set to be in place by the party’s conference in early October.

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Some ministers are already calling for somebody else to act as a caretaker PM over the summer, while others believe Mr Johnson should take on the role for the security of the country.

Some fear if he stays on Mr Johnson could take decisions on key areas like tax and Northern Ireland that might be opposed by possible successors.

One option some cabinet members think is more acceptable is Deputy Prime Minister Dominic Raab taking over as caretaker – however similar concerns about him enacting major policy decisions would also arise.

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Business Secretary Kwasi Kwarteng said “we now need a new leader as soon as practicable”, while recently-resigned science minister George Freeman agreed a “caretaker prime minister should be appointed”.

Bim Afolami, who quit as vice-chair of the Conservative Party, also agreed and Ruth Davidson, former Scottish Tory party leader, said there was “no way” he can stay until October.

“It’s arrant nonsense to think he can. Someone needs to grip this,” she added.

Tory MP Aaron Bell, who is on the procedure committee and fixed-term parliaments act committee, said it would “not be tenable” for Mr Johnson to continue as a caretaker PM “if he cannot fill the ministerial appointments he needs to”.

SNP leader Nicola Sturgeon was vociferous in her opposition to the idea, saying the notion “seems far from ideal, and surely not sustainable”.

Sir Ed Davey, leader of the Lib Dems, was even more incredulous, saying: “The idea that the Conservatives might make Boris Johnson caretaker for anything is frankly ludicrous.

“The man’s never taken care of anything in his life.”

Labour leader Sir Keir Starmer reacted to the news Mr Johnson will be resigning by taking the chance to say the UK does “not need to change the Tory at the top – we need a proper change of government”.

He added: “It should have happened long ago. He was always unfit for office.

“He has been responsible for lies, scandal and fraud on an industrial scale. And all those who have been complicit should be utterly ashamed.”