Just a few days after signing Arsenal's striker Robin Van Persie, Manchester United has completed the transfer of Alexander Buttner from Vitesse Arnhem.

The 23-year-old Dutch defender has signed a five-year deal with Manchester United for an undisclosed fee and has completed his medical.

"Alexander is one of the best young left backs in Europe and we're delighted to sign him. He's someone we've been watching for a while now. He gives us some really exciting options in that position," Manchester United official site quoted club manager Sir Alex Ferguson as saying.

"Joining Manchester United is one of the best days of my life. It's a team I have admired for many years now and I can't wait to join my teammates and play my part in helping the club be successful," Alexander Büttner told Manchester United official site.

Arsenal had earlier confirmed that Robin van Persie would be moving to Manchester United.

"Arsenal Football Club can confirm that terms have been agreed for the transfer of Robin van Persie to Manchester United," reads a statement in Arsenal official site.

"Van Persie will travel to Manchester on Thursday in order to agree personal terms and complete a medical ahead of the proposed move."

Manchester United signed Arsenal's Robin van Persie for a whopping £24 million last week and introduced him in Monday night's match against Everton in which the club lost 1-0.

Manchester United had earlier announced that the Dutch player would move to Old Trafford from Arsenal soon.

"Manchester United is pleased to announce it has reached agreement with Arsenal Football Club for the transfer of Robin van Persie. The deal is subject to a medical and the agreement of personal terms. A further announcement will be made in due course," said a statement from the club.