City have a long-standing interest in Ait-Nouri, but neighbours United also admire his talents.
And the player’s agent, Jorge Mendes, has received ‘firm offers’ from both Manchester giants.
According to Foot Mercato, Ait-Nouri flew to England on Tuesday and visited the facilities of several clubs, including United and City.
Ait-Nouri returned to France after 24 hours in England and has yet to decide his next destination.
He could become the most expensive sale in Angers history if he departs during the transfer window.
The record is currently held by Jeff Reine-Adelaide who was sold to Lyon last summer for €25m + €2.5m in add-ons.
Within Angers, there is an acceptance that the teenage full-back will be leaving the club soon.
To prepare for his departure, Angers spent €3m to sign Souleyman Doumbia from Rennes last month.