A knee injury hindered Fortune's seven-year United career

The 29-year-old and agent, Francis Martin, met Celtic's chief executive.

And Martin said: "I spoke to Peter Lawwell and he said, because of Quinton's injury history, Celtic could only offer him a one-year deal.

"Celtic had some concerns about his scans, but it was more to do with his injury record."

South Africa international Fortune had been invited to visit Celtic Park by former United team-mate Roy Keane, who on Monday announced he was being forced to retire through injury.

And, while Fortune had been impressed by the Scottish champions, his agent stressed: "Quinton did not want to uproot his family and bring them to Scotland just for one year.

We understand Celtic have to be sure about a player Agent Francis Martin

"He is the type of person who would move lock, stock and barrel to a new club, not go somewhere and stay in rented accommodation.

"So he wants to stay in the north-west and will probably sign for Manchester City or Bolton.

"Peter said Celtic will see how he goes in the next season.

"All the clubs have offered much the same and if other interested parties had offered Quinton three or four years then Celtic's 12-month offer would have been a concern for us.

"But we understand Celtic have to be sure about a player and it is just one of those things.

"I would like to thank Celtic for the way they conducted themselves. They could not have been more accommodating."

A Celtic spokesperson said: "Due to Quinton's medical history, Celtic offered the player a short-term contract with a view to assessing his situation going forward.

"Quinton has also been offered short-term deals elsewhere and, given this situation, he has decided to remain at home in the North West of England for domestic reasons, as opposed to relocating to Glasgow.

"Celtic fully understand this and wish him well."

Fortune can also play at left-back, which was a problem position for Celtic manager Gordon Strachan during his championship-winning first season in Glasgow.

Celtic have also been linked with left-backs Michal Kadlec, of Sparta Prague, Everton's Gary Naysmith and Steve Hammell, who has rejected a new contract with Motherwell.