Wales rugby league international Danny Jones has died after suffering a suspected cardiac arrest in Sunday's League 1 match between Keighley Cougars and London Skolars.
Keighley half back Jones collapsed shortly after being replaced in the early stages of the contest at the White Hart Lane Community Sports Centre.
The game was duly abandoned as Jones received treatment from the match doctor and paramedics before being taken to the Royal Free Hospital.
A Rugby Football League (RFL) statement confirmed the 29-year-old, a married father of five-month-old twins, passed away at the hospital, despite "extensive efforts to resuscitate him".
RFL chief operating officer Ralph Rimmer said: "It is always devastating when someone so young dies in these circumstances. Danny was a popular and talented rugby league player, having played at the highest level with the Wales national team and playing over 12 seasons for Keighley Cougars and Halifax.
"The rugby league community will mourn his loss and I wish to extend our deepest sympathies to Danny's family and friends at this incredibly sad time.
"The family, friends and team-mates of Danny are currently and will continue to be supported by the RFL Benevolent Fund and Sporting Chance.
"We would ask that the privacy of the Jones family, players and Keighley Cougars staff be respected."
A message from Keighley's official Twitter account read: "The club are devastated to announce the tragic loss of Danny Jones.
"Danny was much loved and highly respected by all at the club and in rugby league.
"He was the life and soul in the dressing room, a natural leader, a true professional and irreplaceable.
"He achieved over 1000 points and 150 appearances for Keighley Cougars and he will be sorely missed. We are devastated."