An apparatus (5) for twisting a first string (10) of wrapped and spun tobacco leaves into a second string (20) of twisted tobacco leaves defines a first axis (30) extending substantially in the direction of the first string. The apparatus (5) includes a set of rollers (40, 50, 60) each defining a respective circumferential twisting surface (41, 51, 61) for contacting the first string, the circumferential twisting surfaces (41, 51, 61) being arranged so as to substantially confine the first string (10) therebetween so as to rotate the first string (10) and to cause the first string (10) to rotate and be twisted by means of the twisting surfaces (41, 51, 61), and simultaneously to cause the second string (20) to be conveyed along the first axis (30) and out of the apparatus (5).