Canada has said it will stop providing protection for the Duke and Duchess of Sussex in the coming weeks when they step down as working royals.
Meghan and Harry have spent much of the past three months living in the Commonwealth country and plan to make it their base when they quit royalty and become financially independent from March 31.
But there has been speculation about who will pay the bill for keeping the couple and their baby son Archie safe, with Canadian Prime Minister Justin Trudeau facing questions about the issue in recent weeks.
Former Home Office minister Norman Baker called for the Met Police to cap the annual expenditure on security for Harry and Meghan to its 2019 level, with any extra costs met by the couple or the Queen and Prince of Wales.
In a statement Canada's Office of the Minister of Public Safety said: "The Duke and Duchess of Sussex choosing to relocate to Canada on a part-time basis presented our government with a unique and unprecedented set of circumstances.
"The RCMP (Royal Canadian Mounted Police) has been engaged with officials in the UK from the very beginning regarding security considerations.
"As the Duke and Duchess are currently recognised as Internationally Protected Persons, Canada has an obligation to provide security assistance on an as-needed basis.
"At the request of the Metropolitan Police, the RCMP has been providing assistance to the Met since the arrival of the Duke and Duchess to Canada intermittently since November 2019.
"The assistance will cease in the coming weeks, in keeping with their change in status."
Buckingham Palace declined to comment on the development as did Scotland Yard with a spokeswoman saying "we don't discuss matters of security".
Harry and Meghan's new website has a question and answer section for visitors, and in response to the posed question "Does their future financial autonomy extend to covering the costs of security?", the site attempts to give an explanation.
It states: "The provision of armed security by the Metropolitan Police is mandated by the Home Office, a ministerial department of Her Majesty's Government, responsible for security and law & order."
In an update to the website published last week, the portal adds: "It is agreed that the Duke and Duchess of Sussex will continue to require effective security to protect them and their son.
"This is based on the Duke's public profile by virtue of being born into the royal family, his military service, the duchess' own independent profile, and the shared threat and risk level documented specifically over the last few years.
"No further details can be shared as this is classified information for safety reasons."
Mr Baker, a former Liberal Democrat MP, said: "For the Met to have to provide full security abroad will significantly impact on their ability to look after London and Londoners.
"Do we want the Met's budget devoted to tackling terrorism, knife crime, assaults and burglary in the capital, or do we want them flying around the US and Canada, accompanying Harry and Meghan as they enrich themselves through their commercial activities?"
The duke and duchess plunged the royal family into a period of crisis when they announced in January they wanted to step back as senior royals and become financially independent – a move dubbed Megxit by the press.
A summit of senior royals was later convened by the Queen at Sandringham to discuss the issue, with Harry sitting down for talks with his grandmother, father the Prince of Wales and brother the Duke of Cambridge.
It was later announced they would give up royal duties, split their time between Canada and the UK, with the majority spent in North America, no longer be known as HRH, and their lives as working royals would end on March 31.