Queen Elizabeth II
Queen Elizabeth IIReuters

Queen Elizabeth’s doctors "are concerned for Her Majesty’s health and have recommended she remain under medical supervision," a notice from Buckingham Palace said.

The recommendation was made "following further evaluation on Thursday morning," the palace said, adding that, "The Queen remains comfortable and at Balmoral."

Queen Elizabeth II, aged 96, on Wednesday postponed a meeting with senior government officials, after her doctor advised her to take it easy and rest.

In March, Queen Elizabeth said that her bout of COVID-19 had left her "very tired and exhausted."

In June, Daniela Elser, a royal expert, said that, "fading away before our very eyes."

"The difference is truly startling," Elser said. "In the intervening 12 months, Her Majesty would appear to have become markedly more stooped, much thinner and overall appears to have shrunk."