Charles, 72, who underwent an emergency heart operation on January 6, was operated on at Milan’s San Carlo hospital. Italian papers report the operation took place on Monday and say that Charles’ condition was “unstable.”
Staff at San Carlo hospital were unable to comment. Charles is expected to be flown to a hospital near his home in Yorkshire this week.
Charles, who won three Italian titles with Juve after making his name with Leeds United, fell ill before a scheduled appearance on Italian TV programme “Sports Sunday” on January 4.
The Welshman, dubbed the “Gentle Giant” by Italian fans, spent five seasons at Juventus after arriving in 1957, scoring 93 goals in 155 league appearances. Charles won 38 caps for his country and played for them in the 1958 World Cup finals in Sweden.