However, Allardyce has criticised the decision to make an early assessment over the injury, claiming that the Toffees must wait until the issue settles down before determining whether the Icelandic international will return before the end of the season.
At a press conference, Allardyce told reporters: "Whoever gave that statement out is going to get a right telling off because you cannot predict a length of injury in its entirety. You have people who heal quicker. We've got a highly qualified medical staff and equipment to try and speed up any injury.
"I've always felt it's the wrong thing to do, to tag an injury for its time limits because people recover quicker than others.
"For me, it's how the injury is in the next two weeks. When you sustain a knee injury, there's a settling down period immediately afterwards and then it's how quickly the player recovers."
Sigurdsson - who has contributed four goals and three assists in the Premier League this season - is looking to return to full fitness before the World Cup.