The Daily Mail claim the 23-year-old passed the tests in Los Angeles yesterday after negotiations between United and Juventus over a £100m deal were agreed.
The report adds Pogba will be handed the number six shirt which is currently vacant.
The 31-year-old earned 120 caps for Germany, with his final appearance coming in their 2-0 Euro 2016 semi-final defeat to France.
He said: "Dear fans of the Germany national team, I have asked the head coach not to consider me for selection for the national team in the future as I would like to retire.
"I give my thanks to the fans, the team, the German FA and the coaches of the national team. In 120 international games I was allowed to have beautiful and successful moments beyond description for my country.
"Joachim Low knew how much Euro 2016 in France meant to me because I wanted to win this title, which Germany had not won since 1996. It was not meant to be, and I have to accept that.
"To win the World Cup in 2014 was a historic and also emotional achievement, which I will not be able to repeat in my career.
"This is why it is right and sensible to break away from the team now and wish the team all the best for qualification and the 2018 World Cup."
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