Michael Wittstock opened up about his daughter Princess Charlene of Monaco's health for the first time as she continues to recuperate in a medical facility.

The former Olympic swimmer still has not returned to public duties after she reunited with her family in Monaco on Nov. 8. She was grounded in South Africa in May due to a severe ENT infection that required surgeries. She is said to be recuperating mentally and physically at an undisclosed treatment centre outside of Monaco.

Her husband, Prince Albert of Monaco, did not give an estimated timeframe on when her treatment will end. But he shared his hope that the public will let her heal in peace and away from the tabloid rumours surrounding her health.

Now Princess Charlene's father has spoken up about her condition in an interview with South Africa's YOU magazine. He said his daughter is in a "very vulnerable" state. But he remains optimistic that she will come out of her health battle stronger because she is tough.

Wittstock remembered how she trained back when she was an Olympic swimmer and said, "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 75-year old shared that he and the princess' mother Lynette were unable to visit their daughter while she was in South Africa. He said it was for precautionary measures given the COVID-19 pandemic and considering Charlene's condition.

[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," he said adding that they "spoke regularly on the phone."

As for his grandchildren, twins Prince Jacques and Princess Gabriella, Wittstock said that he speaks with them and that they have "a great relationship."

As Princess Charlene continues to recover, Prince Albert of Monaco has also shut down speculations concerning her health. He had since clarified that she is not suffering from COVID-19 or cancer-related problems. It also does not have anything to do with their relationship amid rumors that there is trouble in their marriage.

Prince Albert and Princess Charlene of Monaco
Prince Albert and Princess Charlene at an environmental gala in Monaco in September last year. Photo: POOL / ERIC GAILLARD POOL / ERIC GAILLARD