Manchester United manager Sir Alex Ferguson has called for Zeki Fryers's move to Tottenham Hotspur to be investigated.

The 20-year-old agreed a reported £3m deal on Thursday from Belgian club Standard Liege.

Fryers was due to join Tottenham from United for free in the summer, but the Red Devils' request for £6m in compensation scuppered the switch.

The defender subsequently went to Liege before Spurs picked him up six months later for what Ferguson believes was a cut price.

"There's nothing we can do about it but we should really register our discontent," The Scot told MUTV. "The registration should be stopped.

"To me, I think it's a blatant manipulation of the rules. Tottenham did nothing wrong as he went to Standard Liege. They tried to buy him off us and we'd been looking for a certain figure. They wouldn't pay it but asked if they could take him down there on trial and, at that time, he was out of contract in June anyway.

"So he went down on trial and he went to Portugal with them. They then said they weren't prepared to pay the money and, all of a sudden, he signed for Standard Liege. We knew immediately and suspected that he would return to Tottenham in January and that's happened."

Fryers joined United's youth ranks in 2009 before signing professional terms two years later.