Rishi Sunak has confirmed his interim shadow cabinet, after 12 members of his top team lost their seats in the general election.

Ex-Prime Minister Lord Cameron, who had made a surprise return to cabinet in November, has resigned and been replaced by his former deputy Andrew Mitchell as shadow foreign secretary.

Richard Holden has also resigned as party chairman, after what he described as a “very tough set of results”, and is replaced by former Economic Secretary to the Treasury Richard Fuller as interim chairman.

Many of the key briefs remain unchanged, with Jeremy Hunt named as shadow chancellor and James Cleverly as shadow home secretary, mirroring the portfolios they held in government.

However, James Cartlidge has been appointed shadow defence secretary and Ed Argar shadow justice secretary, after Grant Shapps and Alex Chalk lost their seats.

The Conservatives now have only 121 MPs – the lowest number in the party’s history – after losing 251 seats in a Labour landslide.

Writing on social media, Lord Cameron said: “It’s been a huge honour to serve as foreign secretary, but clearly the Conservative Party in opposition will need to shadow the new foreign secretary from the Commons.”

He added: “As a committed Conservative I will continue to support the party and help where I can as we rebuild from the very disappointing election result.”

As a peer, Lord Cameron did not face his opposite number in the Commons.

In other changes:

• Former Business Secretary Kemi Badenoch moves to shadow secretary of state for levelling up, housing and communities, after Michael Gove stood down as an MP
• Kevin Hollinrake, previously postal affairs minister, takes her place as shadow business secretary
• Andrew Griffith, previously a minister in the department, becomes shadow secretary of state for science, innovation and technology
• Former schools minister Damian Hinds becomes shadow education secretary, after Gillian Keegan lost her seat
• Former Home Office minister Chris Philp is named shadow leader of the House of Commons, after Penny Mordaunt was ousted in Portsmouth North
• Helen Whately, a former health minister, becomes shadow transport secretary
• Julia Lopez is appointed shadow secretary of state for culture, media and sport, after Lucy Frazer lost her seat

Among those who will continue to shadow their former posts are Oliver Dowden, as deputy leader of the opposition, Victoria Atkins as shadow health secretary and Claire Coutinho as shadow secretary of state for energy security and net zero.

Interim party chairman Richard Fuller said: “The Conservative Party has had a difficult election and it is important that we regroup and reflect on these results.

“We should also challenge ourselves candidly and deeply on the strengths of the Conservative Party across the country and outline where improvements can be made.”

In his resignation letter Mr Holden, who held the previously safe Conservative seat of Basildon and Billericay by just 20 votes, said it had been “the greatest honour of my life” to be party chairman.

He said there needed to be a “thorough review” of the election campaign, adding: “While I will obviously feed into that, this would best take place with a new set of eyes to help provide the clearest view.”

Mr Sunak has said he will stay on as party leader until arrangements for selecting his successor are in place.

The timetable for this remains unclear and no Tories have confirmed they will run to replace him yet.

Among the figures tipped to stand are former immigration minister Robert Jenrick, former Home Secretary Suella Braverman, shadow health secretary Ms Atkins and new shadow levelling up secretary Ms Badenoch.

The other positions confirmed are:

• Mel Stride, shadow work and pensions secretary
• Steve Barclay, shadow secretary of state for environment, food and rural affairs
• Jeremy Wright, shadow attorney general
• Alex Burghart, shadow secretary of state for Northern Ireland
• John Lamont, shadow secretary of state for Scotland
• Lord Davies of Gower, shadow secretary of state for Wales
• Stuart Andrew, opposition chief whip
• Laura Trott, shadow chief secretary to the Treasury
• John Glen, shadow paymaster general
• Tom Tugendhat, shadow security minister
• Andrew Bowie, shadow veterans minister
• Mims Davies, shadow women and equalities
• Lord True, shadow leader of the House of Lords