Toby Alderweireld has twice rejected a new Spurs deal because of a dispute with club chiefs over a release clause.
The Belgian centre-back is insisting on a release clause before he signs a new contract, according to the Times.
If Spurs wish to extend his current deal beyond 2019 then Alderweireld has the right to a £25.3million release clause which can be activated from that year.
Club bosses have rejected his demand so far resulting in stalled negotiations.
Man City have been placed on red alert, with Pep Guardiola interested in the 28-year-old as well as team-mates Kyle Walker and Danny Rose.
Serie A giants Inter Milan are also ready to swoop this summer.
The Italian club have been taken over by wealthy Chinese owners and preparing to spend over £150million in the summer.
Alderweireld currently earns around £53,000 a week and knows he can at least double his wage by leaving Mauricio Pochettino’s title challengers.
He has been one of the side’s most important players over the past couple of seasons, forming a particularly solid partnership with fellow countryman Jan Vertonghen.
Alderweireld has been a key contributor to Spurs’ tight defence in the league, conceding just 22 goals all season – the fewest in the top flight.
Pochettino’s worries have grown deeper after Walker told the club he wants to leave.
The England right-back was on the bench for the North London derby win and FA Cup semi-final defeat to Chelsea.
Barcelona and both Manchester clubs are said to be interested.