Britain's Prince Philip dies at age of 99

Britain's Prince Philip, Duke of Edinburgh and husband of Queen Elizabeth II, has died aged 99, Buckingham Palace said on Friday.

"It is with deep sorrow that Her Majesty The Queen announces the death of her beloved husband, His Royal Highness Prince Philip, Duke of Edinburgh," the palace said in a statement.

"His Royal Highness passed away peacefully this morning at Windsor Castle. Further announcements will be made in due course. The Royal Family join with people around the world in mourning his loss."

The Duke of Edinburgh, as he was officially known, had been by his wife's side throughout her 69-year reign, the longest in British history.

A Greek prince, he married Elizabeth in 1947, playing a key role in modernizing the monarchy in the post-World War II period, and behind the walls of Buckingham Palace being the one key figure the Queen could turn to and trust.

"He has, quite simply, been my strength and stay all these years," Elizabeth said in a rare personal tribute to Philip made in a speech marking their 50th wedding anniversary in 1997.

"I, and his whole family, and this and many other countries, owe him a debt greater than he would ever claim, or we shall ever know."

The couple had four children: Charles, Prince of Wales (born in 1948), Princess Anne (1950), Prince Andrew (1960) and Prince Edward (1964), three of whose marriages ended in divorce.

(With input from Reuters)