Prince Philip of Britain is expected to stay in a London hospital over the weekend, a Buckingham Palace source told AFP on Friday, three days after the 99-year-old was admitted after feeling unwell.

Formally known as The Duke of Edinburgh, he is being treated in the private King Edward VII Hospital in Marylebone, central London.

“The Duke is expected to stay in hospital over the weekend and into next week,” the source said.

The prince remains “in good spirits,” they added, while details of his illness are not being made public.

However, the palace reiterated on Wednesday that Prince Philip was admitted as a “precautionary measure” on the advice of his doctor.

The prince was able to walk into the hospital unaided after arriving in private transport rather than an ambulance, a source said at the time.

He was not thought to have contracted coronavirus. Both he and Queen Elizabeth II received the first doses of a COVID-19 vaccine in January.

The prince was initially expected to remain in the hospital for a “few days of observation and rest”, while the latest update suggested his stay was being extended.

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Police officers continued to stand outside the doors of the hospital on Friday.

The latest update on Philip’s health came as Buckingham Palace made a major announcement Friday regarding Prince Harry and his wife Meghan Markle.

The palace said the couple would not return as working members of the royal family after they stepped back from frontline duties last year and subsequently settled in California.