Tottenham's move for Ajax defender Jan Vertonghen is being hindered by a contract clause.

It is claimed Vertonghen is due a percentage of any transfer fee - but sources suggest Ajax are not willing to pay this.

"We all hoped for a rapid agreement between Tottenham Hotspur and Ajax and Spurs and Jan Vertonghen," Ajax financial director Jeroen Slop told De Telegraaf.

"It's in its final stage, but in our opinion there is still no concrete news."