The Princess of Monaco, 43, remains in a “very vulnerable” condition, Charlene's father, Michael Wittstock, has revealed as she remains at a private clinic outside of Monaco. However, Mr Wittstock remained optimistic about his daughter's health battles, referring to Charlene's former career as an Olympic swimmer.

       He told South Africa's YOU magazine: “My daughter used to swim 20km a day.

       “Based on the way she used to train, I know she's tough and will get through this and come out much stronger.”

       The Monegasque Princess finally returned to her family on November 8 after spending six months in South Africa due to a serious ear, nose, and throat infection.

       However, shortly after her return the mother of two was forced to cancel her public appearance at Monaco’s National Day ceremonies and Prince Albert revealed to a local newspaper that she left the principality to seek further medical care.

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       Mr Wittstock also revealed that he and his wife Lynnette Wittstock were not able to visit their daughter during her stay due to Covid concerns.

       He continued: “[There are] our ages—we have to be very careful.

       “I also didn’t want to possibly infect her because she’d been through so many medical procedures and was vulnerable.

       “We spoke regularly on the phone and I speak with the twins.

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       “We have a great relationship.”

       Upon Charlene's return from South Africa, Prince Albert told People the Princess was “overwhelmed and couldn't face official duties, life in general or even family life”.

       He continued: “She has lost a lot of weight, which made her vulnerable to other potential ailments.”

       “A cold or the flu or God help us, COVID. Because I know there are rumors out there, let me say: This is not COVID.

       “And it's not cancer-related. It's not a personal relationship issue.

       “And if you want to discuss another speculation, it isn't related to plastic surgery or facial work at all.”