Prince Philip is being treated for an infection and is not expected to leave the hospital for several days, Buckingham Palace confirmed on Wednesday.

According to the palace, the 99-year-old is "comfortable and responding to treatment."

Philip's youngest son, Prince Edward, told Sky News that his father was "a lot better."

The 56-year-old said, "he’s looking forward to getting out, which is the most positive thing, so we keep our fingers crossed."

The news comes one day after his grandson Prince William said the Duke of Edinburgh is "OK" and doctors are "keeping an eye on him."

PRINCE WILLIAM SAYS HIS GRANDFATHER PRINCE PHILIP IS ‘OK’ AND DOCTORS ARE ‘KEEPING AN EYE ON HIM'

Prince Philip is currently at London's King Edward VII Hospital. (AP)

On Saturday, Prince Charles visited his father, who was admitted on Feb. 16 to London's King Edward VII Hospital for "observation and rest" after falling ill. 

William’s father arrived at the hospital by car and stayed for about half an hour. According to the hospital’s website, visits are only allowed in "exceptional circumstances" because of the coronavirus pandemic.

Buckingham Palace called Philip’s admission "a precautionary measure" taken on the advice of his doctor. His illness is not believed to be COVID-19 related. Philip and his wife, Queen Elizabeth II, received the first dose of the vaccine against the coronavirus in early January. 

Philip retired from public duties in 2017 and rarely appears in public. His most recent public event was a military ceremony at Buckingham Palace in July.

PRINCESS EUGENIE NAMED SON AFTER PRINCE PHILIP AND DISTANT ROYAL GRANDFATHER

Queen Elizabeth married Prince Philip on Nov. 20, 1947, at Westminster Abbey in London. (Chris Jackson/Pool via AP)

During England’s current coronavirus lockdown, the duke has been staying at Windsor Castle, west of London, with the queen, who has performed duties such as meetings with dignitaries remotely.

Lockdown permitting, the royal household is planning celebrations, to mark Philip’s 100th birthday on June 10.

Philip married the then-Princess Elizabeth in 1947 and is the longest-serving royal consort in British history. He and the queen have four children, eight grandchildren and nine great-grandchildren.

A former naval officer and keen polo player, Philip enjoyed robust health well into old age but has had a number of health issues in recent years.

In 2011, he was rushed to a hospital by helicopter after suffering chest pains and treated for a blocked coronary artery. In 2017, he spent two nights in the King Edward VII hospital and was hospitalized for 10 days in 2018 for a hip replacement.

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The first official picture after the announcement of the engagement of Princess Elizabeth and Lieutenant Philip Mountbatten, the former Prince Philip of Greece, at Buckingham Palace.  (Photo by Hulton Archive/Getty Images)

Philip was last hospitalized in December 2019, spending four nights in the King Edward VII Hospital for what the palace said was planned treatment of a pre-existing condition.

He was forced to give up driving at the age of 97, after smashing into a car while driving a Land Rover near Sandringham estate in January 2019. Philip needed help to get out of the Land Rover but wasn’t injured. A woman in the other vehicle suffered a broken wrist.

Even after that, Philip continued to drive a horse and carriage on private land from time to time.

The Associated Press contributed to this report.