Glider, Towplane Tangle

May 4/13-The Montreal Soaring Council Burkhart Grob glider (C-GLTQ) with an instructor and student on board, was being towed to altitude by the Montreal Soaring Council Cessna 305A (C-FERD). At an altitude of approximately 3000 ft ASL the student flying, veered the glider towards the tow plane instead of away from the tow plane. The tow rope had not been released and the tow plane slowed down sufficiently for the glider to begin overtaking it. The tow rope became lodged on the aircraft between the right aileron and the wing. The rope eventually failed and both aircraft returned safely to the field. The Cessna 305A sustained aileron and wing damage.