The England international has been struggling since he picked up the injury in a pre-season tournament in Amsterdam against Ajax, according to manager Sir Alex Ferguson.

"He has never recovered from the tackle in Amsterdam," Ferguson said.

"He's not completed a match since last season and we have had to bite the bullet."

Scholes was at the centre of controversy when he was ruled out of the England squad to face Portugal on Saturday through injury - but then played for United against Middlesbrough.

England coach Sven-Goran Eriksson admitted he was "surprised" to see Scholes in action.

But Ferguson insisted Scholes was injured, and now he will join captain Roy Keane on the sidelines.

Along with domestic fixtures, Scholes will also miss the start of United's Champions League campaign, which opens against Maccabi Haifa at Old Trafford on 18 September.

He could also be ruled out of England's Euro 2004 qualifiers against Slovakia and Macedonia from 12-16 October.

Scholes has been booked in for surgery on his knee and misses the home game against Bolton Wanderers on Wednesday.

It is a severe blow to United's midfield resources, with Keane also facing a possible six-week absence after an operation on a hip injury.

Ferguson is now left with only four of the six midfielders he relies on first choices - Ryan Giggs, David Beckham, Nicky Butt and Juan Sebastian Veron.

Beckham is also fighting to overcome a calf strain picked up in the same game against Middlesbrough on 3 September.

Ferguson said: "We still have options in midfield and hopefully the injury situation will sort itself out in the next few weeks."