Robin van Persie
Robin van Persie leaves the field on a stretcher. [Reuters]

Manchester United have confirmed that they will be unable to call upon the services of Robin van Persie for the next four to six weeks due to a sprained knee.

The Dutch international was stretchered off the field during the Red Devils' 3-0 victory over Olympiacos in the Champions League at Old Trafford last Wednesday.

After playing down the seriousness of the injury, David Moyes revealed that Van Persie would undergo further scans to determine the seriousness of the problem. However, the outcome has come as a blow to the Glaswegian who is set to lose his star striker for at least the next six fixtures in all competitions.

"Following further investigation Robin van Persie has a sprained knee, which will keep him out for around four to six weeks," United spokesperson told the club's official website.

This is the second major setback for United and Van Persie this season as the 30-year-old was ruled out for a similar duration between last December and January. The former Arsenal striker is certain to miss Saturday's Premier League clash against West Ham United before the Manchester Derby at home on Tuesday.

Van Persie will also be unavailable for both legs of the Champions League quarterfinal fixtures against Bayern Munich next month. The striker netted a hat-trick to help the reigning English champions overcome a 2-0 deficit against Olympiacos in the last-16 stage in Europe.

The Dutchman is United's joint highest goal-scorer in the league this campaign alongside Wayne Rooney with 11 goals in 18 appearances so far.