The decision rests with the British Prime Minister and Home Secretary Priti Patel.
Sources told the Evening Standard the review of the Met's protection of Prince Andrew was ordered once it was revealed he was being sacked in November last year.
"Those in charge of royal security cannot write a blank cheque for anyone who does not have a public role for the foreseeable future. Around-the-clock armed protection is very expensive.
"The Met is obliged to review the position to ensure it is justified."
The Duke, 59, may now have to either fund his own bodyguards or go without security.
It's not known what the cost of the royal family's security is, but it's thought to be around £100 million (nearly $197 million NZD) a year.
Taxpayers are said to have forked out over £250,000 ($492,000 NZD) for the Duke's security team's travel expenses when he was promoting his Pitch@Palace scheme.
A Home Office spokesman would not comment on individual security arrangements.
The Sun also contacted Buckingham Palace for comment.
Harry and Meghan's security costs are also being reviewed after they stepped down from their roles as senior royals. Photo / File
Andrew continues to face the backlash following the BBC interview which saw him admit he didn't regret his friendship with convicted sex offender Jeffrey Epstein and show no empathy for Epstein's victims.
He's barely been seen in public since them, and many have cut ties with him.
His private secretary Amanda Thirsk, who advised him to do the Newsnight interview, quit last week with a payout worth several thousand dollars. She'd been employed by the royal household for 15 years.
There's also questions surrounding Prince Harry and Meghan Markle's security costs after they announced they were stepping down as senior royals to spend time in Canada.
Their current security bill of around £600,000 (nearly $1.2 million NZD) a year could at least double if protection officers have to be dispatched to Canada.
It's been reported that the Canadian government have offered to pay part of the costs.
Canadians are divided over the issue, with some enraged that the government is considering footing the Sussexes' security bill - which could add up to millions a year.
