Baleba is reportedly United's top target for a new midfielder before the summer transfer window closes.
His interest in joining United may have been hinted at through a social media post from Leny Yoro, a United defender, who mentioned the team's progress in preseason.
Baleba and Yoro have a strong friendship, as they previously played together at Lille.
Brighton is insisting that Baleba will not leave the team for less than £100 million.