LONDON - Members of the British royal family rushed to be by the side of Queen Elizabeth after doctors said they were concerned about the health of the 96-year-old monarch on Thursday, saying she should remain under medical supervision.

The queen, Britain’s longest-reigning sovereign and the world’s oldest monarch, has been suffering from what Buckingham Palace has called “episodic mobility problems” since the end of last year.

She has been forced to cut back on her public engagements since then and on Wednesday, cancelled a planned virtual meeting with senior ministers after being advised to rest by her doctors.

“Following further evaluation this morning, The Queen’s doctors are concerned for Her Majesty’s health and have recommended she remain under medical supervision,” the palace said in a statement.

“The queen remains comfortable and at Balmoral.”

A palace source said immediate members of the British royal family had been informed and played down speculation that the monarch had suffered a fall.

Elizabeth has been queen of Britain and more than a dozen other countries, including Australia and Canada, having ascended to the throne as a 25-year-old in 1952. 

Earlier this year, she marked her 70th year on the throne with four days of national celebrations in June.

“I have been inspired by the kindness, joy and kinship that has been so evident in recent days, and I hope this renewed sense of togetherness will be felt for many years to come,” she said at the time.

Queen Elizabeth's husband, Prince Philip, died last year at the age of 99. 

Singapore was a British colony, and under the symbolic rule of Queen Elizabeth, until it became a founding member of Malaysia in 1963 before gaining full independence in 1965.

Prince Charles, the heir to the British throne, is now with Queen Elizabeth after she was placed under medical supervision, the BBC reported.

The Prince of Wales and his wife Camilla, the Duchess of Cornwall, had travelled to Balmoral Castle in Scotland after receiving news from the doctors.

Queen Elizabeth’s grandson Prince William and her sons Princes Andrew and Edward have arrived in Scotland by plane to be with the ailing monarch, television footage showed on Thursday.

Prince William, who holds the title of the Duke of Cambridge, is second in line to the throne.

The Duke of Sussex is travelling separately to Balmoral. A spokeswoman said his wife Meghan was not accompanying him, the BBC reported.

The pair, who quit royal duties in 2020 to live across the pond in California, have been back in England since Saturday for a series of charity engagements.

The Queen's daughter, Princess Anne, was already at Balmoral.

Such a family gathering, outside of holiday events such as Christmas or Easter or major public events, is extremely rare.

Last October, Elizabeth spent a night in hospital and she has been forced to cut back on her public engagements since then.

On Wednesday, the queen was forced to cancel a planned virtual meeting with senior ministers after being advised to rest by her doctors.

The previous day she had been pictured appointing Liz Truss as the country’s new Prime Minister at her Scottish home, Balmoral Castle.

Ms Truss is the 15th premier of Queen Elizabeth's reign.

Minutes before making her statement, Ms Truss was handed a note in the House of Commons where she was revealing her plans to cap energy bills, The Daily Mail reported.

“The whole country will be deeply concerned by the news from Buckingham Palace this lunchtime,” the Prime Minister said.

“My thoughts – and the thoughts of people across our United Kingdom – are with Her Majesty The Queen and her family at this time.”

Mr Keir Starmer, the leader of Britain’s opposition Labour Party, said he was deeply concerned about news that Queen Elizabeth’s health had declined.

“Along with the rest of the country, I am deeply worried by the news from Buckingham Palace this afternoon,” he said in a statement.

Britain’s Parliament has Queen Elizabeth in its thoughts and prayers following news that doctors were concerned for her health, speaker Lindsay Hoyle said in Parliament on Thursday.

“I know I speak on behalf of the entire House when I say we send all the best wishes to her Majesty the Queen,” Mr Hoyle said.

“My prayers, and the prayers of people across the #churchofengland and the nation, are with Her Majesty The Queen today,” Justin Welby, the Archbishop of Canterbury, said on Twitter. REUTERS