Queen Elizabeth II dies aged 96

Queen Elizabeth II, the longest-serving monarch in British history and an icon instantly recognisable to billions of people around the world, died on Thursday. She was 96.

Buckingham Palace announced her death in a short statement, triggering 10 days of national mourning and an outpouring of tributes to her long life and record-breaking reign.

"The Queen died peacefully at Balmoral this afternoon," Buckingham Palace said in a statement at 6:30 pm.

"The King and The Queen Consort will remain at Balmoral this evening and will return to London tomorrow."

The eldest of her four children, Charles, Prince of Wales, who at 73 is the oldest heir apparent in British history, becomes king immediately.

The queen's death came after the palace announced on Thursday that doctors were "concerned" for her health and recommended she stayed under medical supervision.

All her children -- Charles, Princess Anne, 72, Prince Andrew, 62, and Prince Edward, 58, flocked to her Scottish Highland retreat, Balmoral.

They were joined by Charles's sons, Prince William, and his estranged brother Prince Harry.

Two days earlier the queen appointed Liz Truss as the 15th prime minister of her reign and was seen smiling in photographs but looking frail and using a walking stick.

One photograph of the meeting sparked alarm, showing a deep purple bruise on the monarch's right hand.