Banned former Fifa president Sepp Blatter believes the World Cup should not be used as an occasion to experiment with video replay technology.
Blatter's comment on Twitter followed a series of confusing incidents involving the Video Assistant Referee (VAR) system which is being trialled in the FA Cup, Italy's Serie A, Germany's Bundesliga, the Portuguese league and other competitions around the world.
The sport's law-making body Ifab is due to decide on Saturday whether to approve VAR on a permanent basis and Fifa has already said it intends to use the system at the World Cup in Russia in June and July.
"A personal appeal to Ifab the Guardians of the Laws of the Game: FIFA WC cannot be used as experiment for such a fundamental change: VAR," said Blatter.

The latest confusion involving VAR was last night's FA Cup match between Tottenham Hotspur and Rochdale, where the London side had an early goal disallowed and a penalty later awarded by the VAR.
Afterwards, Tottenham manager Mauricio Pochettino said VAR risked killing emotion in the sport, echoing a sentiment which has already been expressed by some Serie A coaches.
It was not clear if Blatter was appealing for IFAB to reject VAR outright or give it more time.
Blatter quit after 17 years as FIFA president in June 2015 after the global soccer body was engulfed in a corruption scandal. The 81-year-old was later banned from the sport for six years for ethics violations.
Blatter, who has always denied wrongdoing, told Reuters last month he was considering legal action to clear his name. Last week, he tweeted his support for Morocco's bid to host the 2026 World Cup.