The Arsenal right-back signed a six-year deal in October 2016, but attempted to engineer a return to Barcelona last summer.
Reports earlier this month claimed the Spain international is determined to quit the Gunners at the end of this season, having noted the improvement in Alex Oxlade-Chamberlain’s performances since quitting Arsenal for Liverpool.
It is claimed that Arsenal’s stance has softened and the north London club is willing to entertain bids in the region of £50million for the 22-year-old in order to help finance their own summer recruitment drive.
The Manchester Evening News reports that United have already made contact with Bellerin’s camp and have asked to be made aware should there be any significant developments.
Should they formally enter the running, United are likely to face competition from Barcelona and Juventus.
United’s shock defeat to Sevilla in the Champions League on Wednesday has only hardened Jose Mourinho’s resolve to strengthen his squad in the close season, with reinforcements in midfield and defence his priority.
Antonio Valencia has filled in as a makeshift right-back again this season, but the Ecuador international turns 33 in August and Matteo Darmian has already been deemed surplus to requirements.