Toby Alderweireld's agent says the Tottenham defender deserves "a correct contract" or a move away from the club.
The Belgium international's deal is due to expire in 2019 but progress over a renewal appears to have stalled in recent months.
It is reported that Spurs are reluctant to trigger a one-year extension option as this would activate a release clause that would allow him to leave for the relatively small fee of EUR25million.
But the centre-back's agent, Stijn Francis, has suggested that a failure on Spurs' part to offer a suitable new deal will see him attempt to force a transfer.
"Toby is always good. Even after his injury he recovered well. Tottenham's statistics fell sharply during his absence," he told Het Nieuwsblad.
"If you only look at his figures, Toby is impressive and for his performances, he deserves either a correct contract from Tottenham or a transfer.
"For a transfer, you know that he can only leave Tottenham for seven or eight teams and almost all the other top clubs are interested in Toby.
"There are not a lot of central defenders of his kind, so they are sought after. But those clubs also know that they have to negotiate with [Spurs chairman] Daniel Levy."
Danny Rose caused a storm during the transfer window when he went public with his criticism of Spurs' wage structure and transfer policy, although he later offered an apology.
The club broke their transfer record to bring in defensive reinforcements last month, signing Davinson Sanchez from Ajax for an initial fee of EUR40million.
Mauricio Pochettino's side also brought in young centre-back Juan Foyth from River Plate and full-back Serge Aurier from Paris Saint-Germain.