Jose Mourinho has conceded there are "some players in world football" whom Manchester United will always try to sign amid interest in Arsenal forward Alexis Sanchez.
United are looking to rival Manchester City for the 29-year-old and Standard Sport understands both clubs at varying stages of discussions over a January move.
Arsenal are hoping to receive around £40 million for a player out of contract in six months but City have indicated they are unwilling to go higher than £20m.
When asked by United's interest, Mourinho told reporters: "Sanchez is an Arsenal player, I don’t know but probably this weekend he is going to defend Arsenal colours so I don’t think it’s correct to say things about Alexis Sanchez.
“At the general level what I can say is myself and the Manchester United board, the owners, we don’t believe a lot in the January market, we don’t believe in signing a player just to sign a player, just to do something, we don’t believe in that.
“What we believe really is there are some players in football world if you have the chance to sign them in January, in March or in July, you have to try and that’s it.
“But in relation to Alexis Sanchez I don’t say a word, the only word I can say is he is a phenomenal player, apart from that an Arsenal player and I feel I shouldn’t say much more than this.”
