Hargreaves was plagued by injuries, having had operations on both knees, in the latter stages of his United career and made just four appearances in three seasons.

However, in a shock move Mancini is considering giving the former Bayern Munich player a chance with what would, considering his history, most likely be a pay-as-you-play deal.

Hart, at an England press conference ahead of Friday’s Euro 2012 qualifier with Bulgaria, was asked about the possibility of Hargreaves joining.

“It would be a good signing. Obviously, Owen Hargreaves has done great for Bayern Munich,” he said.

“He has struggled a bit since he came to Manchester United but that is not down to ability, just his fitness.

“If he can get himself fit and does sign for Manchester City, it can only be a positive.

“He was a very important England player. If he can get back to that form, obviously he would be an asset.”

Hargreaves, voted England’s best player in the World Cup in Germany in 2006, joined United from Bayern Munich for £18m the following year.

He played in the 2008 Champions League final victory over Chelsea in Moscow but then began to suffer with knee problems, restricting him to four appearances in three seasons.

Hargreaves lasted just 10 minutes of his comeback against Wolves last September and United opted not to renew his contract as a result.

If he were to sign for City it would add some defensive solidity to a side which has been boosted by the arrivals of striker Sergio Aguero and Sami Nasri this summer.

Wayne Rooney said he wished his former United and England team-mate good luck as he tried to relaunch his career.

“He’s been out for a couple of years now and he’s worked hard to try to get back,” he told the England press conference.

“He spent a lot of time over in Germany or in the States (for treatment and rehabilitation) and we didn’t see much of him.

“When he came back he played one game and unfortunately got another injury, to his hamstring.

“He’s a nice lad and he’s worked extremely hard to get back playing, but the manager thought he didn’t want to keep hold of him.

“I wish him luck and I hope he gets back. Everyone knows that when he’s fully fit he’s a great player, he’s a different type of midfielder to what we’ve had in England.

“We all hope as England players and fans that he can one day get back to his best.”