Former FIFA president Sepp Blatter has claimed that the decision to use the video assistant referee (VAR) system at this summer's World Cup is "not very clever".
Blatter's permanent successor, Gianni Infantino, confirmed in March that world football's governing body had approved the use of VAR at the finals in Russia.
However, the 82-year-old - whose 17-year spell in charge at FIFA ended amid a corruption scandal in 2015 - believes that fans "don't feel comfortable" with the system.
"For a purist in football, as I am, I think it is an innovation which is going too fast," Blatter is quoted by BBC Sport as saying.
"Most of the referees have never worked this system. To go to the World Cup and introduce this system in the World Cup, I think it is not very clever.
"I don't feel comfortable, definitely not, and spectators don't feel comfortable."
Blatter was banned from football for eight years by FIFA following the 2015 scandal, a term later reduced to six years after appeal.