Sir Keir Starmer has insisted none of the budget leaks and leadership speculation has come from him - as he vowed to "get to the bottom" of the briefings.

The prime minister told parliament's liaison committee a leak to the Financial Times 13 days before the budget, revealing a proposal to increase income tax had been dropped, was "unacceptable".

"It was not a briefing that was signed off by me or any of my ministers or officials," he told the committee, which is made up of the chairs of select committees.

"It was unacceptable."

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Asked about claims certain cabinet members are trying to replace Sir Keir as prime minister, he said: "I can say, hand on heart, that none of it comes from me or is encouraged by me."

He said briefing against cabinet ministers is "completely unacceptable" and said he has "made that repeatedly clear to my staff, to the cabinet".

The prime minister said he has put in place "a number of procedures" to "give me a level of assurance" that ministers, his team and staff are not the ones leaking.

He said he has "no reason to believe" anybody in Number 10 leaked the plan to no longer increase income tax.

Other budget details were also leaked, including a pay-per-mile levy on electric vehicles and a tourist tax.

She said the leaks were "very damaging" and "we cannot allow this to happen again".

Ms Reeves said a review of Treasury processes is taking place and she has brought in the National Centre for Cyber Security to carry out a forensic examination of IT systems, after the Office for Budget Responsibility's assessment of the budget was accessible before she had announced it