When asked if Sanchez is a player United want this month, the Portuguese said: "I don't think it is ethical or correct to be speaking about players of other clubs.
"If somebody speaks about one of my players, to say we are interested or not I wouldn't be very happy.
"Sanchez is an Arsenal player. I don't know but probably this weekend he is going to wear Arsenal colours. I don't think it is correct to say things about Alexis Sanchez.
"At a general level, what I can say is that myself and the Manchester United board, we do not believe a lot in the January market. We don't believe in signing a player just to do something.
"What we believe is there are some players in the football world where, if you have a chance to sign them, whether it is in January, March or July, then you have to try.
"In relation to Sanchez all I can say, which everyone else says, is that he is a phenomenal player. I feel I shouldn't say much more than this."