The death of the 96-year-old sovereign, the longest-serving monarch in British history, was announced while Thursday's first round of the European Tour's flagship event was still in progress at the Wentworth course, southwest of London.

"Out of respect for Her Majesty and the Royal Family, play has been suspended at the BMW PGA Championship at Wentworth Club for the remainder of Thursday and flags at Wentworth Club will be lowered to half-mast," said a European tour statement. 

"Furthermore, no play will take place at the BMW PGA Championship on Friday and the golf course and practice facilities will be closed. 

"Further updates on the resumption of play will be provided in due course."

England's Andy Sullivan and Tommy Fleetwood, together with Norway's Viktor Hovland, were the joint clubhouse leaders at eight under par, after the trio all shot rounds of 64, when play was suspended.

The tournament had been taking place against the backdrop of the bitter civil war in golf sparked by the creation of the 'rebel' LIV Tour.

Several players from the Saudi-backed LIV series are competing at Wentworth this week, a decision four-time major champion Rory McIlroy, who has remained loyal to the established European and US PGA tours, said he found "hard to stomach".

McIlroy shot 68 on Thursday.