An automobile vehicle seat includes a seat pan adjustable in height in relation to a support frame attached to the floor of the vehicle and an attachment point for a seat belt attached to the seat pan. A cable element is attached by one end to the support frame and the seat pan includes locking means adapted to allow the cable to slide during the voluntary variations in height of the seat pan in relation to the frame or, alternatively, to block the cable element by jamming during a high deceleration so as to prevent the seat pan from moving up in relation to the support frame.