A circular knitting machine for the production of an opened fabric tube comprises a needle cylinder (1), a frame (6), which is coupled to the needle cylinder (1) and in which at least a draw-off roller (4) and/or a take-up roller (5), drive means (36 to 43) to drive said roller, and a blade (19) intended for opening the fabric tube are each rotatably mounted, and a flexible shaft (21), which is rigidly connected to the blade (19) and a drive wheel (38), for setting the blade (19) in rotation at a rotational speed dependent on the knitting speed. According to the invention, the drive wheel (38) of the flexible shaft (21) is functionally connected (FIG. 2) to the drive means (36 to 43) for the draw-off and/or take-up roller (4, 5).