Manchester United have rejected Owen Hargreaves' claims he was incorrectly given injections to cure knee problems during his time at the club.[LNB] In the aftermath of Wednesday's Carling Cup win for Manchester City against Birmingham, when Hargreaves marked his Blues debut with a goal, the 30-year-old outlined the unhappiness over sections of the treatment he received to combat a tendinitis injury he had before leaving Bayern Munich in 2007.[LNB]Hargreaves said in the end, he felt like "a guinea pig" such were the revolutionary treatments he was forced to undergo in an effort to solve a problem he felt had been exacerbated by the injections.[LNB]Sir Alex Ferguson mounted a staunch defence of his medical staff earlier today.[LNB]Now United have released a full statement, in which they dismiss Hargreaves' claims and state they remain "comfortable" with the treatment the midfielder received.[LNB]"United does not acknowledge any validity in the comments Owen is alleged to have made," said the statement.[LNB]The statement continued: "Manchester United is disappointed with Owen's remarks after the game on Wednesday.[LNB]"The club gave him the best possible care for three years and is as disappointed as anyone he was not able to play a part in the team's success at that time.[LNB]"It has shared all the medical records with Manchester City and is comfortable with the actions taken by its medical staff at each step of his many attempts at rehabilitation.[LNB]"Manchester United has some of the best sports medical staff in world sport, who have made a significant contribution to United's on-pitch success in recent seasons."[LNB]Earlier, Ferguson was adamant any criticism of his back-room team was completely without foundation.[LNB]"Do you think we would be successful if they were not 100% brilliant? Our doctor and his five physios are fantastic - that is my opinion and that is more important than what anyone else has to say about it," said the Scot.[LNB]Hargreaves underwent surgery on both knees during the 2008-09 season.[LNB]Following the operations, Hargreaves played just six minutes of first-team football as he battled to regain fitness and was eventually released by United in the summer.[LNB]But he has achieved full fitness barely three weeks after joining City on a free transfer and claimed on Wednesday the medical treatment he received at United did more harm than good.[LNB]"I received some injections but my tendon was never the same," he said.[LNB]"After the injections, I tried to get back on my feet and they said my tendon was good, but it felt like I was made out of glass.[LNB]"With my tendon injury, I've had to be a guinea pig for a lot of these treatments. All the people there [at United] are lovely and everybody tries their best, but at times you come to a certain point where you need to make a decision.[LNB]"I wanted to play. Everyone wanted me to play, so it's not really an option to say, 'sit it out and rest for six months'. With hindsight it's a lot easier, but I wish I had not had the injections."[LNB]Aware of the delicate nature of the matter, City manager Roberto Mancini opted to tiptoe carefully through the row this morning, although he confirmed Hargreaves is now pain free.[LNB]"There are no problems, apart from a bit of tiredness," Mancini said.[LNB]"He has been out for two years, which is a long period. He has worked hard for the last six months in Canada. And I hope it has solved all his problems.[LNB]"I don't think they (United) got it wrong. I just hope he will be lucky in the next two years.[LNB]"After something like this, it can happen that after one or two games he might have a problem with his ankle or hamstring or something.[LNB]"But I remember him very well when he played for United and Bayern. He was an incredible midfielder.[LNB]"United paid £17million for him and he is 30 years old. On top form he is one of the best midfielders in Europe."