Ranieri, who guided Leicester to the Premier League title last season, was dismissed on Thursday, less than 24 hours after a 2-1 Champions League defeat against Sevilla in Spain.

Reports of player unrest have since emerged, with claims that Ranieri was sacked after the club owners met senior squad members in the wake of the defeat against the reigning Europa League champions.

Mourinho wore a specially-printed shirt at his weekly news conference at United on Friday bearing Ranieri's initials and proceeded to condemn the actions of those he believed led to the Italian losing his job.

"When I was sacked as a champion [by Chelsea], it was a giant negative thing," Mourinho said. "But now I know it was peanuts in comparison.

"Nobody can delete what Claudio did. If some of the stories [about the players] are true, or just a little bit true, it is difficult to find words to justify that.

"Probably the season started with a typical selfishness of others -- people thinking of new contracts, leaving, more money, forgetting who helped them reach a certain level.

"This is not just football. It is part of the world. Some principles are going away.

"I lived a similar experience, but peanuts compared to Claudio's. But maybe it is Claudio's fault. He is paying for his success."

Mourinho, who replaced Ranieri at Chelsea following his sacking by Roman Abramovich in 2004, made his shirt tribute after posting an Instagram message in support of his former rival.

"My word is my shirt," Mourinho said, pointing to the "CR" initials on his top. "My little homage to the man who wrote the most beautiful story of the Premier League.

"Somebody who deserves the Leicester stadium to be named after him -- the Claudio Ranieri Stadium.

"Leicester made history two years in a row -- the most beautiful story and now they are also in the highlights for a decision that has everyone in football united because it is very difficult to accept.

"It is important that we realise this is football and we have to adapt."