Andy Carroll is likely to miss the rest of the season after West Ham announced the striker is to undergo surgery on a knee injury.

The 26-year-old was forced off in Wednesday's 0-0 draw at Southampton and Hammers boss Sam Allardyce had hoped Carroll would be sidelined for a maximum of six week.

But the club announced on Friday afternoon that their club-record signing requires an operation, with the lasting implication being that he is unlikely to play again this season.

"Andy Carroll will have surgery on his injured knee on Tuesday following assessment by a specialist on Friday afternoon," a brief statement on West Ham's official website read.

"The England international injured his left knee during the second half of Wednesday night's 0-0 Barclays Premier League draw at Southampton. The recovery phase is expected to keep Carroll out for the remainder of the 2014/15 season."

Speaking to the press on Friday morning before the full extent of the injury was known, Allardyce was hopeful to have had the forward back in his squad inside two months.

"It is likely to be a few weeks, the medial ligament on the side of his knee has a tear in it from a fairly innocuous collision. He is wearing a brace," Allardyce said.

"I would have thought four to six weeks out if we are lucky, depending on Andy's recovery. Some players heal quicker than others. It is a big blow for him and us. It is another blow we have to cope with."

That blow is now much bigger than Allardyce would have been expecting as he looks to lead the Hammers to a top-half finish in the Premier League and take them on a run in the FA Cup – with a fifth-round meeting at West Brom on Saturday lunchtime.