Son was linked with a move to Saudi Arabia two years ago, but rejected advances to stick around for the start of Ange Postecoglou's tenure.
Postecoglou subsequently named Son as Spurs captain and last month the South Korean forward led the team to Europa League success to achieve his goal of winning silverware at the club.
Speculation over Son's future has been rife during his 10th season at Tottenham and whilst the club triggered a 12-month option in his deal in January, he is set to enter the final year of his contract in July.
Son will also turn 33 next month and was affected by injury problems during the 2024-25 campaign, but the Premier League club will only let their talismanic skipper leave for a significant transfer fee, PA understands.
Spurs are set to visit South Korea again later this summer for their pre-season - the third time in four years they have travelled to Son's homeland to prepare for a new campaign.
Even though Son, who is currently on international duty, only managed 11 goals last term - his lowest return since his debut season - his global status offers enormous commercial value to the club.
Son is not the only key figure with an uncertain future with no clarity over Australian head coach Postecoglou, who remains in the dark as to whether he will get a third season at Tottenham.
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