It has previously been claimed that United boss Jose Mourinho is keen to bring the versatile England international to Old Trafford as he looks to strengthen his first-team squad ahead of next season.
Spurs do not want to sell a player who only penned a new five-year deal in 2016, but according to The Mirror, United are ready to test their resolve with a bid of £60m.
Dier has allegedly signalled a willingness to make the move to the North-West of England, but it is unlikely to change Spurs' stance on the 23-year-old.
The 23-year-old made 46 starts in all competitions last season, but he was used in both defence and midfield after Victor Wanyama was often preferred to him in the centre of the park.
Spurs have also already sold Kyle Walker to Manchester City and despite the money on offer for his signature, the North Londoners cannot afford to let another key player leave for a rival.