LABOUR have called for the review into how Boris Johnson’s refurbishments of his Downing Street flat were financed to be expanded to investigate whether the public was misled over the renovations.

No 10 declined on Tuesday to deny suggestions that the Prime Minister received a loan from the Conservative Party to cover the initial costs, before repaying the party.

But that claim appears to run contrary to what Johnson’s then press secretary Allegra Stratton said last month when she denied any party funds were used for refurbishments.

After Johnson was accused of lying by Labour, deputy leader Angela Rayner urged Cabinet Secretary Simon Case to expand his review to investigate the comments.

She urged him to probe “whether the former press secretary knowingly misled journalists and the public, or was misled herself by senior members of the Government who seem intent on a cover-up”.

The Prime Minister was facing continued questions of how the works were paid for, after former aide Dominic Cummings said Johnson wanted donors to “secretly pay” for the work in an “unethical, foolish, possibly illegal” move.

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The Tories declined to deny a suggestion, first reported by ITV, that the Conservative Campaign Headquarters (CCHQ) paid the Cabinet Office to cover initial costs of the refurbishments, with Johnson now repaying the party.

The Prime Minister’s official spokesman said: “Any costs of the wider refurbishment in No 10 have been met by the Prime Minister and he has acted in accordance with the appropriate codes of conduct and electoral law.”

He was pressed on a denial by the Prime Minister’s former press secretary Allegra Stratton in a Westminster briefing with journalists on March 8.

“Conservative Party funds are not being used to pay for any refurbishment of the Downing Street estate,” she had said.

But asked about suggestions to the contrary on Tuesday, Johnson’s spokesman said: “I’ve seen the reports and the speculation on that, I’m not going to jump ahead of any potential declarations that need to be made.”

Case, the head of the Civil Service, has been tasked with reviewing the refurbishment of the flat in No 11.

In a letter to the Cabinet Secretary, Rayner said: “As a special adviser, Allegra Stratton is bound by the Civil Service Code, which sets out standards of integrity and honesty required from public officials.

“Therefore, I would urge you to build into your review an investigation into whether the former press secretary knowingly misled journalists and the public, or was misled herself by senior members of the Government who seem intent on a cover-up.”

Stratton, who moved roles this month after No 10 scrapped plans to hold televised press briefings fronted by the former journalist, is yet to respond.

Shadow health secretary Jonathan Ashworth called for a “full and frank” explanation from the Prime Minister.

“We really need to know who’s given the loan, who’s given the money, because we need to know who the Prime Minister, who Boris Johnson, is beholden to,” the Labour MP told BBC Breakfast.

“To be honest he lied yesterday – that’s not good enough.”

Downing Street was moved to issue a further defence of Mr Johnson later in the day, but it also stopped short of ruling out a loan from CCHQ.

“Any costs of wider refurbishment this year beyond those provided for by the annual allowance have been met by the Prime Minister personally. Conservative Party funds are not being used for this,” a spokeswoman said in a statement.

Labour has said that the “stench” surrounding the issue “will only grow” unless Johnson publishes the long-delayed list of ministers’ interests.

Johnson’s spokesman said that list, last published in July, would not be updated until after No 10 appoints a new independent adviser on ministerial standards.

Sir Alex Allan resigned from the role in November in response to Johnson standing by Home Secretary Priti Patel despite an investigation finding her conduct “amounted to behaviour that can be described as bullying”.

“The declaration of interests that will be made available once we’ve appointed the replacement for Alex Allan, that work is in train,” the spokesman said.

“One of the first things that person will then do is then look at the ministerial interests and then make sure they can be published in the normal manner.”

An update of the separate register of MPs’ financial interests on Tuesday showed no sign of a loan to Johnson, with his only addition a £2397 payment for book royalties. Last week the Daily Mail published details of an email from Tory peer Lord Brownlow in which he said he was making a £58,000 donation to the party “to cover the payments the party has already made on behalf of the soon-to-be-formed ‘Downing Street Trust’”.

Labour has called for a full investigation by the Electoral Commission.

It comes as rules around Whitehall staff holding second jobs  were tightened in the wake of the Greensill Capital row.

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An investigation prompted by revelations Bill Crothers worked for three months as both Government procurement chief and an adviser for Greensill Capital found no instances of officials holding outside interests which conflicted with their roles.

Fewer than 100 senior civil servants held paid employment outside Whitehall and “the overwhelming number” of top officials acted in accordance with the rules.

But Simon Case set out a series of steps to tighten the rules, including requiring all senior civil servants to set out relevant interests to the head of their Whitehall ministry on at least an annual basis.

These returns would be scrutinised by audit and risk committees and each Whitehall department would be required to complete an annual return to the Cabinet Office.

Departments’ annual reports would also include a register of relevant interests for board members, including senior civil servants.

Case said he was considering whether “new structures need to be established” to oversee the situation.

The Cabinet Office had also been working with the Advisory Committee on Business Appointments (Acoba) to improve the “operation and efficacy” of the rules governing the jobs former officials took up.

Crothers left the civil service in November 2015 but had begun an advisory role at Greensill Capital in September that year and later became a director of the firm.

Case told the Public Administration and Constitutional Affairs Committee (PACAC) it was a “pretty extraordinary set of circumstances” that took place before his time as the head of the civil service.

“We cannot explain how these decisions were taken or why,” he told MPs.

“That’s why they are of acute concern.”