Manchester United have completed the signing of former Barcelona goalkeeper Victor Valdes on a free transfer.

Valdes has been training at United since October as part of his bid to recover from a knee injury he suffered in March.

The Spaniard has now regained full fitness and United confirmed he had signed a deal with the club.

“Manchester United is delighted to announce that Victor Valdes has signed an 18-month contract with the option to extend for a further year,” a statement from the club read.

Valdes left Barcelona last summer following a successful 12-year spell with the Catalan giants.

Valdes won six domestic titles, three Champions Leagues and lifted the Copa del Rey on two occasions while with Barca.

The goalkeeper has also won the World Cup and European Championship with Spain.

Louis van Gaal confirmed, however, that Valdes will start his time at United as second choice behind compatriot David de Gea, who has enjoyed a superb season so far.

“He joins the club as the number two goalkeeper and is a great addition to the first team,” the United boss said.

Van Gaal handed Valdes his Barca debut 13 years ago and has been impressed by the goalkeeper’s attitude during training sessions at United’s Carrington base.

“I am delighted Victor has signed for the Club,” Van Gaal said.

“Victor is a very experienced goalkeeper and his record speaks for itself. I have said on many occasions that Manchester United will always be interested in the best players.

“Victor has remained very professional throughout his rehabilitation from injury and has been very impressive during his training sessions with the first team over the past weeks.”

Valdes said it was an “honour” to sign for United, but acknowledged he faces an extremely tough fight to earn a first-team place at Old Trafford.

“I think now, in the moment, (De Gea) is the best goalkeeper in the world,” Valdes told MUTV.

“His performances every day and in every game shows everybody that his level is very high. He has had a great year and it is very nice.”

Valdes does not appear to have any qualms about being De Gea’s deputy.

“I am here to help everybody,” he said. “Always in my career, I have played to help my team-mates, to help my coach and to help everybody.

“I am a part of the team and I am not a problem, I am just a part of the team.”

On being reunited with Van Gaal, Valdes said: “I would like to thank Louis van Gaal and the club for allowing me to do my rehabilitation and to train with the team at the Aon Training Complex.

“From my short time here I can already see this is a very special club. I worked with Louis van Gaal during my time at FC Barcelona and to have the opportunity to work with him here at Manchester United is a dream come true.”

Valdes’s signing is likely to increase the chances of Anders Lindegaard leaving the club in January.

Lindegaard, 30, was linked with a move away from the club last summer but stayed.

United’s 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 Van Gaal for letting in Miralem Pjanic’s 60-yard lob against Roma in pre-season.