The Red Devils have already tied up a deal to sign Memphis Depay from PSV Eindhoven next month as Louis van Gaal looks to transform his side into genuine Premier League title contenders for next season.
United have been linked with a host of players in recent weeks, including the likes of Real Madrid winger Gareth Bale and Tottenham star Harry Kane.
And the Arsenal boss is expecting United to make significant reinforcements during the summer transfer window.
Wenger told a news conference on Friday morning: “I expect Manchester United to be active in the transfer market. Every player I am offered, Manchester United are already on his case!
“He [Van Gaal] has shown that he has the personality to be at a club of that size. We expect them to buy some strong players.”
Arsenal head to Old Trafford in the Premier League on Sunday looking to return to winning ways after their surprise 1-0 defeat by Swansea City at Emirates Stadium on Monday night.
The north London side are currently third in the table heading into their final three Premier League games of the season.
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