Klose suffered the injury in a Carabao Cup defeat by Crawley on 27 August.

The club said scans showed "significant damage to the posterior cruciate ligament in Klose's right knee".

Meanwhile, defender Christoph Zimmermann's foot ligament injury is still being assessed, while midfielder Tom Trybull is set to be out for six weeks with ankle ligament damage.

Zimmermann and Trybull were injured in the 2-0 Premier League defeat at West Ham last Saturday.

Norwich manager Daniel Farke said: "It is a blow for us and the players, but these are some of the challenges we have to face right now."