Sky Sports News understands United are interested in the Belgium international, with Spurs pricing the defender in excess of £50m.
The 29-year-old has one year left on his current contract, with an option for a one-year extension that includes a £25m release clause for next summer, but talks over a new deal have continued to stall.
At this stage, sources understand United forward Anthony Martial, who has told Jose Mourinho he wants to leave, is unlikely to end up at Spurs despite the club’s long-standing interest in him, meaning United would need to meet the full asking price for Alderweireld.
However, United do not share Spurs’ valuation of a player with a year left on his current contract.
Any potential move for Alderweireld is expected to go to the final days of the window, which closes on August 9 for Premier League clubs.
Earlier this month, Alderweireld said his prolonged spell out of Tottenham’s first-team last season was “unjustified”, while he admitted he was still unsure about his future.
Another potential outcome is that Alderweireld and Tottenham could yet agree terms on a new contract but that is looking increasingly unlikely, according to Sky sources.
Jose Mourinho is looking to bolster his defensive options ahead of the new season. On Wednesday, Sky Sports News reported United have approached Leicester regarding England centre-back Harry Maguire.
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