Hargreaves, who made an outstanding goalscoring debut for rivals Manchester Cityon Wednesday night, claimed he felt like a 'guinea pig' as he was givenseveral injections which he believes actually hindered his recovery from a tendinitis problem that first surfaced during his time at Bayern Munich.
United are considering a formal response, which is expected to be released later today.
My Manchester United agony: Hargreaves claims injections made knee injury worseHargreaves: It's so sad I didn't play a bigger role for United but this is a new chapter Bold move: Owen Hargreaves (right) joined Manchester United's heated rivals at Eastlands this summer
But Ferguson is adamant any criticism of his back-room team is completely without foundation.
'We are trying to analyse all the stuff he has said and there will be a statement later to address that,' Ferguson said. 'As far as I am concerned my medical staff is one of the main reasons why we have been so successful over the last few years.
'Do you think we would be successful if they were not 100 per cent 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.'
Happier times: Hargreaves and Ferguson enjoyed success together at United before injuries hit
Pain game: Hargreaves' attempts at a comeback at Old Trafford ended in yet more injury agony
Hargreaves underwent surgery on both knees during the 2008-09 season. 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.
The 30-year-old claimed the medical treatment he received at United did more harm than good.
'I received some injections but my tendon was never the same,' he said. 'After the injections, I tried to get back on my feet and they said my tendon was good, but it felt like Iwas made out of glass.
'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 cometo a certain point where you need to make a decision.
'I wanted to play. Everyone wanted meto 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.'
Back with a bang: The England midfielder scored a fine goal on his City debut earlier this week
Sharpshooter: Hargreaves scores against Birmingham at the Etihad Stadium on Wednesday
Amazingly, three weeks after signing for City in a shock move shortly before the transfer window closed, Hargreaves was fit enough to play almost an hour in the Blues' Carling Cup win over Birmingham on Wednesday. He even crowned the occasion with a goal, something he only managed twice during his entire time at Old Trafford.
City manager Roberto Mancini opted to tread a delicate path this morning, although he confirmed Hargreaves is now pain free.
'There are no problems, apart from a bit of tiredness,' Mancini said. '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.
'I don't think they (United) got it wrong. I just hope he will be lucky in the next two years.
Too soon? The former Bayern Munich star has already been tipped for an international return by Roberto Mancini
'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.
'But I remember him very well when he played for United and Bayern. He was an incredible midfielder.
'United paid ?17million for him and he is 30 years old. On top form he is one of the best midfielders in Europe.'
Hargreaves will not be considered for Saturday's Premier League encounter with Everton at the Etihad Stadium and is ineligible for Tuesday's Champions League trip to former club Bayern Munich.
Asked about Hargreaves' comments, Arsenal manager Arsene Wenger said: 'The doctor takes the responsibility to treat the players. If the players feel they have been badly treated they have to turn to the medical department - you do not want to interfere with that. I feel that everybody at a club should just not interfere with the next one.
'I never forced anybody to play. I have stopped many who wanted to play and didn't play them. Personally I do not feel concerned by that problem at all. My belief is that if a player is not 100 per cent, do not play him no matter how good he is. I have always stuck to that.'
?My Manchester United agony: Hargreaves claims injections made knee injury worseHargreaves: It's so sad I didn't play a bigger role for United but this is a new chapterMatt Lawton: England won't call Owen Hargreaves yet but it's a great startAll the Premier League team news ahead of the weekendCharles Sale: Sir Alex Ferguson's down the road after 25 yearsAll the latest Manchester United FC news, features and opinionAll the latest Manchester City FC news, features and opinion
Source: Daily Mail
Source: Daily Mail