Munster head coach Anthony Foley has died at the team hotel in Paris, the Irish club have announced.
Former Ireland international Foley was 42 and had been in charge at Munster since July 2014.
He was due to take charge of the team on Sunday against Racing 92, but that match has now been postponed.
Munster said in a statement: “It is with deep regret that the Irish Rugby Football Union and Munster Rugby must advise of the passing overnight of Munster Rugby head coach Anthony Foley, at the team hotel in Paris.”
Foley captained Ireland three times during a 62-cap career, and he skippered Munster to Heineken Cup glory in 2006, with victory over Biarritz in Cardiff.
Munster’s statement added: “Munster Rugby management are liaising directly with Anthony’s family and will provide them with any assistance and support required.
“The IRFU and Munster Rugby pass on our deepest sympathies to all of Anthony’s family and friends and ask for privacy for the family at this sad time.
“As a mark of respect to Anthony and his family and and to support players, management and staff, Munster Rugby have requested that today’s match against Racing 92 be rescheduled.
“Munster Rugby thank Racing 92, EPCR, broadcasters and partners, and the many fans who travelled to Paris for their understanding and support at this time.”
The postponement was confirmed by European Professional Club Rugby (EPCR).
The competition organiser said in a statement: “Due to the tragic passing in Paris of Munster Rugby head coach and former captain, Anthony Foley, today’s European Rugby Champions Cup Round 1 match between Racing 92 and Munster Rugby has been postponed and will be rescheduled.”
EPCR chairman Simon Halliday said: “On behalf of EPCR, I would like to extend my deepest sympathies to Anthony’s family and to everyone associated with Munster and Irish rugby. He was a magnificent player and a superb coach and he will be sorely missed.”
Back-rower Foley made a try-scoring international debut against England in the 1995 Six Nations, but it was from 2000 to 2005 that he became established as a key figure in Ireland’s team.
He made just one substitute appearance at the 1995 World Cup before starting two matches at the 2003 tournament, and last featured in international rugby during the 2005 Six Nations.
He retired in 2008, leaving Munster as the club’s most-capped player with 194 appearances for the provincial side.