Former Barcelona goalkeeper Victor Valdes has accepted an offer to join Manchester United.

The Spain international, who has been training with United in his bid to recover from a serious knee injury, has agreed an 18-month contract.

Valdes, 32, won six La Liga and three Champions League titles with Barcelona, before leaving at the end of last season when his contract expired.

The deal could lead to reserve keeper Anders Lindegaard leaving Old Trafford.

It also poses a question about the future of 24-year-old first-choice goalkeeper David De Gea, who was the club's player of the year last season and has excelled again this term.

His contract is due to expire in 2016, although senior United sources have previously said they were relaxed about him signing an extension to that deal.

Before last season started, Valdes confirmed that it would be his final one at the Nou Camp, although his campaign ended in March when he tore his anterior cruciate ligament, an injury that kept him out of the World Cup.

Manchester United are third in the Premier League, nine points behind joint leaders Chelsea and Manchester City.

De Gea has played in every match for United this season, but conceded four in the League Cup defeat at MK Dons in August and five in thePremier League loss to Leicester on 21 September.

However, the defensive record has improved in the last few months with the club only letting in seven goals in their last 13 matches in all competitions.

Denmark international Lindegaard, 30, arrived at Old Trafford in a £3.5m deal in January 2011, but has only made 19 Premier League appearances.

The other two goalkeeping options are 21-year-old Sam Johnstone, who is on loan at Doncaster, and 24-year-old Ben Amos, who was criticised by United boss Louis van Gaal for letting in Miralem Pjanic's 60-yard lob against Roma in pre-season.