This means she will have been apart from her husband of 73 years for nearly three weeks.
The hospital staff said while they realise how difficult it is for patients and their families amid the pandemic, "our first duty is to the patients we serve, and to maintain their safety at all times we need to control visiting".
The hospital policy continues, "We are only allowing visitors in exceptional circumstances. We understand that having a family member in hospital is distressing, and we work closely with relatives and friends to ease their concerns and find alternative ways of keeping in touch."
Harry and Meghan have been urged to delay their Oprah tell-all in light of Prince Philip's condition.
Trailers promising "shocking" statements from the ex-royals have been released as the 99-year-old Duke was moved to another hospital for tests because of a heart condition, reports the Sun.
Royal sources said the family was "pretty appalled" that the Oprah interview was still going ahead while Philip remains in hospital.
Trailers for the interview show Harry saying he feared Meghan would suffer the same fate as his mother Diana in "history repeating itself".
And the former celebrity talk show host asked Meghan why she thought her time as Duchess was "almost unsurvivable".
Philip is set to turn 100 on June 10 and has been in hospital for two weeks being treated for an infection.
Buckingham Palace said yesterday that he had been moved to St Bartholomew's hospital, also in London, for testing and observation.
Now royal commentators are calling for the interview to be shelved until Philip recovers.
