Jose Mourinho's side will play Vålerenga IF at Oslo's Ullevaal Stadium on July 30.
United had already announced a tour of the United States in July, when they will play LA Galaxy, Real Salt Lake, Manchester City, Real Madrid and Barcelona.
“The team will have access to top-class facilities and the number of games this summer ensures that the manager and squad have the best opportunity to prepare for the coming season,” executive vice-chairman Ed Woodward said in a press release.
“Playing games across a number of locations gives our unrivalled fans the opportunity to watch the team play, with the club being fortunate to have such fantastic support right across the world.”
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