Andrew Mountbatten-Windsor charged taxpayers for the cost of massages and excessive travel expenses while he was the UK’s trade envoy, it has been reported.

Former senior civil servants said they were shocked to see the claims, and that there was a culture of deference towards the former prince within Whitehall that allowed them to proceed.

“I thought it was wrong … I’d said we mustn’t pay it, but we ended up paying it anyway,” a former civil servant told the BBC, referring to a claim that followed a visit to the Middle East.

The source, who worked in the UK’s trade department in the early 2000s and is now retired, said he was annoyed by Andrew’s request to cover the cost of “massage services”, and refused. But he claimed he was overruled by senior colleagues.

He said he regretted Andrew was able to get away with the expense claim when it might have been a chance to check his behaviour. “I can’t say it would have stopped him, but we should have flagged that something was wrong.”

The broadcaster reported that a second source, who oversaw finances in this area, saw similar expense claims for Andrew’s trips and had “absolutely no doubt” about the authenticity of the allegations.

The BBC also reported on claims for the costs of excessive flights, unreasonable numbers of hotel rooms and charges for Andrew’s entourage. “I couldn’t believe it … it was like it wasn’t real money, they weren’t spending any of their own money,” a source said.

The costs reportedly disappeared into different budgets, making them hard to trace, and there was little certainty over who had been in Andrew’s entourage. The culture of deference meant checks on his spending were more “rubber stamp” than scrutiny, according to the sources.

The broadcaster said it spoke to the former civil servants separately. The Guardian has not been able to independently verify their claims and the BBC has not seen proof of the claim about charging for massages. But it said it had seen verified that the whistleblowers’ worked within the area at the relevant time.

A third source also reportedly told the BBC Andrew could be an ineffective trade envoy, whose visits could do more to harm local relations than to enhance them. The former civil servant said: “Andrew was seen as a liability. He went off-script, he thought he was an expert, when he wasn’t. He thought he was funny, when he was being rude to people.”

Mountbatten-Windsor held the post from 2001 until 2011.

The Department for Business and Trade did not deny the claims, referring instead to a statement issued by Thames Valley police last week – after Andrew was arrested – that read: “We continue to assess all relevant information and have no further comment at this time.”

Mountbatten-Windsor was released under investigation after being held by police for more than 10 hours. There is no suggestion that the behaviour described in the BBC’s reports amounts to unlawful conduct by Mountbatten-Windsor. His lawyers have declined to comment.