Correctional Services said that “matters are under control” at Johannesburg’s Sun City Prison on Wed.
Manchester United's Paul Scholes will be out for 10 weeks after suffering medial knee ligament damage in the Champions League win against Aalborg.
The 33-year-old midfielder was stretchered off after just 16 minutes of United's 3-0 victory.
The loss of Scholes adds to United's worries in midfield as Michael Carrick is out for at least another month with a broken bone in his foot.
Striker Wayne Rooney was also forced off with an ankle problem.
Rooney was replaced by Carlos Tevez just before the hour mark as a precaution after injuring his ankle and Ferguson was unsure as to the seriousness of the injury.
"We are hoping it isn't ligament trouble," added the Scot.
"He just felt his ankle. I would imagine he would be doubtful for the Blackburn game on Saturday."
England coach Fabio Capello will be taking a keen interest in Rooney's injury because on Sunday he will be naming his squad for the World Cup qualifiers against Kazakhstan and Belarus.
Cristiano Ronaldo, meanwhile, has admitted it will be another three weeks before he has fully recovered from his summer ankle operation.
The Portuguese winger, who came through his first full 90 minutes against Aalborg, said: "It will be another two or three weeks before I can give 100 percent. I feel very good. There is good improvement there and I am very happy to be back.
"But my ankle has still not fully recovered. I still feel it a little bit. But the medical staff say that is normal and I feel very confident about the future."
There were some plus points for United, notably from Dimitar Berbatov who opened his account for the club with two second-half goals on his Champions League debut. Ferguson was delighted with his contribution. - BBC