Husband of Britain's Queen Elizabeth II, Prince Philip, has been reportedly admitted to a hospital in London on Wednesday as a "precautionary measure".

According to an official statement, the 99-year-old was admitted as a "a precautionary measure, on the advice of His Royal Highness's Doctor" after he felt unwell.

The Duke of Edinburgh "is expected to remain in hospital for a few days of observation and rest," the statement said.

Meanwhile, the Queen, 94, has been maintaining social distancing due to their age. In January, the couple received their first vaccination doses.

Prince Philip retired from public duties in 2017 at the age of 96 following a two-night hospitalisation for an infection. He then had a hip operation in 2018.

The latest hospitalisation renewed concerns about Philip's health ahead of his 100th birthday in June this year.