Sir Alex Ferguson has launched a fierce defence of Wayne Rooney, stating his determination to keep the striker at Manchester United, attacking criticism of his performances as "rubbish" and condemning the Football Association for not treating him fairly.

In a defiant response to a week of speculation over Rooney's future, Ferguson suggested the striker needed to focus more on his club and rethink his willingness to talk to reporters at England press conferences organised by the FA. United's manager not only thinks the player is naive and overly trusting but, in comments guaranteed to rankle with the FA, believes the national body have failed to protect Rooney properly while also subjecting him to overly harsh disciplinary sanctions.

"I keep telling him he's too trusting," said Ferguson. "I told him: 'I don't know why you do it with the FA.' He does things every time he goes down there [with England]. He should not be doing anything with them. They've not helped him one bit. Every time he does anything [commits an on-field offence] they punish him more than anyone in the game. He should be realising that. He shouldn't have to do anything for the FA. They force him to do it."

Ferguson is a master at deflecting attention from issues he does not want to discuss and diverting attention to Rooney's relationship with the FA rather than with his manager appeared a classic example of the art.

He may have failed to find room for Rooney in his Champions League starting line-up against Real Madrid but United's manager still maintains the forward is England's best player.

After dismissing suggestions that Rooney was unfit, overweight and unprofessional as "rubbish", Ferguson suggested that the 27-year-old is a victim of tall poppy syndrome.

"It's because he's a stellar England player," said United's manager, who is adamant that he does not want to sell Rooney and will instead extend the contract of a player expected to start against Chelsea in Sunday's FA Cup quarter-final at Old Trafford.

"He's the Gascoigne, the Bobby Charlton. He's the best English player. You have to contend with that being news and the need to sell papers. For them to suggest I don't talk to him on the training ground is absolute bollocks. It's nonsense. It's an insult to me too but it sells newspapers, what can you do?"

When the subject reverted to the Champions League defeat on Tuesday, Ferguson stressed that Rooney accepted his squad rotation policy. "There's no issues at all," said United's manager. "It's not about one person. The issue was that [Danny] Welbeck was better at that job against people robbing him of the ball. He's very good at that – the best we've got."

Asked whether Rooney would be at Old Trafford next season, the Scot's reply was unequivocal. "There's no doubt about that," he said. "There's no issue with his contract. When it gets time to renegotiate, it will be done. We don't want players to leave.

"Wayne's coming to his mature years [approaching his peak]. He's had a lot of issues this year in terms of illness, injuries and not had a long run of games but he'll get 20 goals, no doubt about that."