SIR Keir Starmer’s election as Labour leader is under renewed scrutiny amid calls for a police probe into the handling of donations by his chief of staff Morgan McSweeney.

Left campaign group Momentum said today that any “improper use of funds” must be investigated immediately, following claims that his top aide hid more than £700,000 of donations used to bring down Jeremy Corbyn’s leadership of the party and install Sir Keir as his replacement.

The Conservatives say private legal advice given to Mr McSweeney contradicts a public claim by pro-Starmer think tank Labour Together that its failure to declare donations stemmed from “human error and administrative oversight” and that it had been as “open and transparent” as possible.

Mr McSweeney declared donations to the group when he took over as director of Labour Together in 2017.

But he stopped reporting donations early in 2018, apart from one disclosure of £12,500 from Trevor Chinn, a businessman and friend of Tony Blair.

It was only after Mr McSweeney left to work for Sir Keir, following the latter’s election as the new Labour leader, that his replacement, Hannah O’Rourke, found that almost three years of donations worth £739,000 had not been declared, leading her to file a series of “late” declarations with the Electoral Commission.

In a letter to the commission, the Conservatives say the legal advice implies that they “chose not to report those donations” to stop the then Corbyn-led Labour Party knowing “who was bankrolling their secretive political campaigning and to keep their work below the political radar.”

Momentum said: “It has been known for years that Starmer’s 2020 leadership election was based on a deception of members.

“If he also received undeclared donations, this would place a major question mark over his legitimacy as leader.

“Improper use of funds must be investigated immediately.”

Deputy Prime Minister David Lammy dismissed the Tories’ claims on Monday as “muckracking.”

A Labour Together spokesman said that it had “proactively raised concerns about its own reporting of donations” to the commission, and since its probe’s conclusion was made public in 2021, “we have taken measures to ensure Labour Together is fully compliant with all Electoral Commission regulations.”

A commission spokeswoman said: “We were satisfied that the evidence proved beyond reasonable doubt that failures by the association occurred without reasonable excuse. Offences were determined and they were sanctioned accordingly.”