Tottenham have been given an ultimatum by Toby Alderweireld's agent - either give the defender improved terms or sell him to another European club.
The Belgian has less than two years to run on his current deal and said in July he had not held talks over a new contract.
His current terms say, if Spurs take up an option to add a year to the length of the contract in 2019, Alderweireld can leave for £25million, something Tottenham want to take out of any new deal.
But Alderweireld's representative, Stijn Francis, says unless suitable terms are offered, the club must sanction a move elsewhere.
"When you look at Toby's statistics, they are impressive. Either he deserves an appropriate contract, or else he should be given a transfer," said Francis, as quoted by The Sun.
"Seven or eight big European clubs are interested in signing him. There are not many central defenders around who can play like he can.
"But these clubs will have to negotiate with Tottenham's chairman, Daniel Levy."
Alderweireld has been away on international duty, and helped Belgium qualify for the World Cup with victory in Greece on Sunday evening.
He admits he is leaving his future in the hands of others as he prepares to return to north London ahead of Tottenham's game at Everton on Saturday.
"I leave everything to my father," he said. "We will see what happens in the coming months. But of course a great deal has happened recently.
"I am going to progress still further. I can really see myself getting a whole lot better. By adapting my game, I have improved every season."