Dier, who enters the final year of his current deal at the end of this season, would also prefer to be played at centre-back rather than in holding midfield.
Spurs chairman, Daniel Levy, is keen to avoid yet another situation where one of the players is at the club with less than 12 months remaining on their contract.
That has recently occurred with Christian Eriksen, who left for Inter Milan during the January transfer window for a cut price fee as a result. Jan Vertonghen is another example, who could leave for free this summer.
Toby Alderweireld was in a similar position, but has since signed a new deal to keep him with Tottenham until 2023.
Dier is concerned about his role in the team under manager Jose Mourinho, having failed to start a Premier League match since Christmas. This lack of minutes could contribute to the 26-year-old missing out on a place in the England squad for Euro 2020.
If Dier decides not to commit his future to the club, then Levy will look to sell him in the summer - with the versatile player understood to be interested in a switch abroad. Although born in England, Dier moved to Portugal as a child and came through the Sporting Lisbon academy.
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