Jose Mourinho says he regrets the way he treated Bastian Schweinsteiger during their time together at Manchester United.

Schweinsteiger, who was signed by predecessor Louis van Gaal, failed to make a single Premier League appearance under Mourinho and left for Chicago Fire this week.

Mourinho acknowledged he mistreated the World Cup winner by leaving him out of the first-team squad and forcing him to train with the reserves.

"[Schweinsteiger] is in the category of players that I feel sorry for something I did to him," he told a pre-match news conference ahead of facing West Brom.

"I don't want to speak about him as a player, as a player I would or would not buy. I want to speak about him as a professional, as a human being.

"It was the last thing I told him before he left: 'I was not right with you once. I have to be right to you now.'

"So when he was asking me to let him leave, I had to say 'yes, you can leave', because I did it once, I cannot do it twice.

"So I feel sorry for the first period with him, he knows that, I am happy that he knows, because I told him. I will miss a good guy, a good professional, a very good influence in training.

"I could not stop him going, even though I know we have so many matches and probably would need him for a few matches or a few periods.

"But I had to let him go and now publicly wish him and his wife a very happy life in Chicago."

Mourinho added that he should have allowed Schweinsteiger to work with the first team, but United's squad was too big.

"I do regret it, yeah," he continued. "I would let him be in the squad [now].

"I know that at that moment we had too many players - if you remember we had many players in these doubtful situations, [Morgan] Schneiderlin, [Memphis] Depay, Andreas Pereira, Tyler Blackett, James Wilson.

"We had a huge squad in the beginning but after knowing him as a person and a professional and the way he was respecting my decisions as a manager, yes I regret it and it is no problem for me to admit it, because I have told him."