Inter boss Antonio Conte is keen to sign Sanchez before the European transfer window closes on Monday.
If a deal goes through, Sanchez will link up with ex-United team-mate Romelu Lukaku, the striker having joined the Serie A club for £74m this summer.
However, Inter have not agreed an option to buy Sanchez at the end of the loan agreement.
United’s highest earner, Sanchez is thought to earn around £400,000 a week, a figure way outside of Inter’s current pay structure.
It has been suggested United may subsidise his salary as part of a deal and last week Inter offered to pay £150,000 of Sanchez’s weekly wages, but United wanted more.
Sanchez has had a disastrous 19 months at Old Trafford since leaving Emirates Stadium in January 2018, scoring just five times in 45 appearances.
He scored twice last season and only once in the Premier League and, should he have stayed at the club, would have predominantly played in the Europa League and Carabao Cup.
Manager Ole Gunnar Solskjaer wants to give more game time to teenage forward Mason Greenwood, who has made three substitute appearances so far this season.