Rachel Reeves has urged Andrew Mountbatten-Windsor to repay taxpayer cash he may have misused while serving as Britain's trade envoy.
The ex-prince has faced allegations of misusing taxpayer money in a number of ways in his role between 2001 and 2011, including on massages, "unreasonable" numbers of hotels, and taxpayer-funded aircraft on RAF bases.
Mr Mountbatten-Windsor was arrested last week on suspicion of misconduct in public office and was released without charge.
Now, asked whether he should pay back money if he is found to have misused it, Mrs Reeves has told The i Paper: "Of course."
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She also admitted she had never met the former Duke of York - and was glad not to have done so.
Concerns were raised by civil servants about the former royal's excessive usage of expense claims on massages.
One former civil servant, who worked in the Department of Business and Trade in the early 2000s, said he regretted that Mr Mountbatten-Windsor was able to expense claim taxpayer money on massages.
The department did not challenge the claims made - but has referred to the ongoing police investigation into the former prince.
Rachel Reeves has urged Andrew Mountbatten-Windsor to repay taxpayer cash he may have misused
|PA
While Mr Mountbatten-Windsor's role as trade envoy was unpaid, he had support from civil servants and taxpayer funding for overseas trips.
The former civil servant, who worked in the former UK Trade and Investment Department, admitted he regretted that Mr Mountbatten-Windsor was allowed to get away with expenses for a massage, believing it could have served as a chance to check his behaviour.
"I can't say it would have stopped him, but we should have flagged that something was wrong," he told the BBC.
Liam Byrne, the chairman of the Commons Business and Trade Committee, said MPs would begin gathering information in order to "stand ready to launch an inquiry" into the former royal's role as trade envoy after the police conclude their investigation.
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PICTURED: Jeffrey Epstein seen with Andrew Mountbatten-Windsor at a party in Mar-a-Lago, 2000 | GETTYWhen asked if she agreed with Trade Minister Chris Bryant's assertions that Mr Mountbatten-Windsor was a "rude, arrogant and entitled man", she said she had never met him and that it was "probably for the best".
Earlier this month, allegations came from former Prime Minister Gordon Brown that Mr Mountbatten-Windsor had used RAF bases to arrange meetings with Jeffrey Epstein.
In a letter addressed to authorities in London, Surrey, Sussex, Thames Valley, Norfolk and Bedfordshire, the former Prime Minister named several airports used by Epstein, including RAF Marham in Norfolk.
He was concerned about a December 2000 incident when Epstein's Gulfstream jet, carrying Ghislaine Maxwell and Epstein himself, landed at the military air base from London Luton airport.
Andrew was arrested last week on suspicion of misconduct in public office
|REUTERS
US Department of Justice files revealed that he landed at Luton on December 6, before flying to RAF Marham the next day with two additional passengers, including one unnamed female.
Epstein and Maxwell then travelled 20 miles to the Sandringham Estate to meet with Andrew.
Several commercial airports were also named in the letter and in DOJ files - including Edinburgh, Belfast, Liverpool, Birmingham, Norfolk, Gatwick, Heathrow, Luton and Stansted.
Bedfordshire Police are now believed to be investigating his links to Luton, but there is concern the airport's files may have been deleted.
Mr Mountbatten-Windsor has denied any wrongdoing over his Epstein links, but has not directly responded to the latest allegations.