The Spain international joined United late in the summer transfer window following injuries to Luke Shaw and Tyrell Malacia.
United originally looked at signing Marcu Cucurella on a temporary basis in their search for cover at left-back, but his appearance for the Blues in the Carabao Cup put paid to that idea.
Erik ten Hag subsequently sanctioned a move for Reguilon, who made 12 appearances in all competitions for the Red Devils during the opening half of a difficult campaign.
With Shaw and Malacia closing in on making their returns, however, United have decided to send the 27-year-old back to his parent club.
United’s schedule will ease in the coming weeks following the hectic festive period, especially given they are out of Europe altogether after their Champions League demise, while their Carabao Cup defence ended in November with a 3-0 defeat against Newcastle.
Shaw and midfielder Sofyan Amrabat, who has also featured at left-back for United this season, were surprise absentees for the 3-2 win over Aston Villa on Boxing Day.
On the pair, Ten Hag later said: ‘One took a knock in training and the other during the match. I don’t think it’s serious.’
Both did not recover in time to be in the squad for the 2-1 defeat at Nottingham Forest four days later.
Reguilon’s place at Spurs has been taken by the impressive Destiny Udogie, meanwhile, and his future at the north London club remains unclear.
Ange Postecoglou’s side remain in the midst of a defensive injury crisis but as Reguilon has only appeared for United this, under FIFA rules, he could still play for another club should he leave again during the transfer window.
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