Britain held a minute's silence on Sunday in a final tribute to Queen Elizabeth before her grand state funeral, after her son King Charles welcomed world leaders at Buckingham Palace.

US President Joe Biden and French President Emmanuel Macron were among the stream of dignitaries who paid tribute at the late monarch's coffin, Biden crossing himself and touching his heart as he stood on a gallery in London's historic Westminster Hall.

The US president then attended a reception hosted by King Charles and the royal family for around 500 visiting dignitaries.

They included Japan's Emperor Naruhito, King Felipe VI of Spain, Brazilian President Jair Bolsonaro, King Abdullah II of Jordan and Queen Margrethe II of Denmark.

The minute of silence was held at 8:00 pm (1900 GMT) to honour the late queen's life of service.

Prime Minister Liz Truss stood in a black dress outside her 10 Downing Street official residence for the "national moment of reflection" before the eyes of the world focus on the British capital for the queen's send-off. (AFP)