United were linked with the 13 year-old Peruvian last week, while Peru sources say Chelsea attempted to sign the midfielder before his family agreed to join Bayern.
Bayern supremo Uli Hoeness admitted Larrauri had not signed any contract: "The reports have been exaggerated. He's coming over for a year to play with the youth team. Nothing has been signed.
"We'll see at the end of the year if the relationship will continue."