The monarch has called Harry, his brother Prince William, and their father Prince Charles to a crisis meeting at her private Norfolk estate of Sandringham where the “next steps” for the couple will be decided on Monday.
It comes after Harry and Meghan released a bombshell statement outlining their plans to step back as senior royals, become financially independent, and split their time between the UK and North America.
The Duke and Duchess of Sussex made the announcement on Wednesday without telling the Queen or other senior royals first.
Meghan, who returned to Canada on Friday to be with the couple’s eight-month-old son Archie, is likely to join the talks via conference call, according to a royal source.
Buckingham Palace said “a range of possibilities” would be discussed, but the Queen was determined to resolve the situation within “days, not weeks”.
Among the details that need to be worked out are who will pay for the couple’s currently taxpayer-funded security, what money-making activities they can undertake and what the tax consequences would be of moving to Canada or the United States.
The crisis talks will take place amid speculation that Harry and Meghan could give a "no-holds-barred" interview which could be "very damaging" for the royal family, who are still reeling from Prince Andrew's links to paedophile Jeffrey Epstein.
"I have some idea of what might be aired in a full, no-holds-barred, sit-down interview and I don’t think it would be pretty," the couple's close friend Tom Bradby, the ITV news anchor, wrote in The Sunday Times.
Royal biographer Angela Levin told Sky News: “The Queen has said she wants [the situation resolved] really fast, and that is because she doesn’t want Harry to go off in a huff, I am sure, and not come back.
“They want to maintain the link of the family. It would be an absolute tragedy if it was done with a very bad feeling.”
However William appeared on the front page of The Sunday Times, which reported that he was sad that he and Harry were “separate entities” because he wanted “everyone to play on the team”.
Harry, who is sixth in line to the throne, married American actress Meghan Markle at Windsor Castle in 2018, and their son was born in May last year.
While many praised the couple for injecting youth and glamour into the royal family, last week’s announcement marked an explosive turn in the growing rift between the couple and the rest of the clan.
Harry said in an October interview that he and William – destined one day to be king – were on “different paths”.
The couple’s shock announcement last week came amid their growing unhappiness about their treatment by the media.
Harry, who blames the press for the death of his mother, Princess Diana, in a Paris car crash in 1997, has long chafed at the intense scrutiny he receives.
The couple have sued several newspapers over allegedly intrusive coverage, and Harry has accused the media of targeting Meghan, who is mixed race, with abuse, some of it with “racial undertones.”
Their decision to distance themselves from the royal family has drawn a mixed reaction from the British public.
Many expressed sympathy for Meghan and Harry but said they should not receive taxpayer-funded security if they do not perform public duties.
There has been widespread sympathy for the 93-year-old Queen, who attended church at Sandringham on Sunday, arriving by car dressed in a camel-coloured coat and hat.
Members of the public gathering near St Mary Magdalene Church said they felt sorry for the Queen, with some saying that Harry and Meghan should not receive any more taxpayers’ money.
Additional reporting by Press Association