Manchester United have confirmed Paul Pogba has joined the Italian champions Juventus, with their manager Sir Alex Ferguson criticising the teenager for a lack of respect and claiming the deal was done "a long time ago".

The French midfielder Pogba, 19, was considered one of the outstanding talents in the club's academy but his future was consistently questioned last year as he rejected offers of a new deal at Old Trafford.

Ferguson has announced the formal end of his time at United, telling MUTV: "Pogba signed for Juventus a long time ago as far as we're aware."

United had presented improved terms – and a promise of improved first-team opportunities – to Pogba, but he was not swayed.

The news left Ferguson, who had nevertheless been expecting the decision, fuming.

"(It) is disappointing. I don't think he showed us any respect at all so, to be honest," he said. "I'm quite happy that if they carry on that way, they're probably better doing it away from us."

Pogba arrived at United from Le Havre in 2009 – a move that infuriated the French side.

He went on to make just seven first-team appearances for the club, all last season and all from the substitutes' bench.

Three of those came in the Premier League and three in the Carling Cup, with a solitary Europa League appearance in a 2-1 defeat to Athletic Bilbao.

Pogba is the second highly-rated young player to leave the club this year after the prodigiously talented but controversial Ravel Morrison was allowed to join West Ham in January.