A shaft plug for a mine shaft, the shaft plug comprising an inflatable bladder adapted to be inflated by pressurised gas, the bladder being adapted to be positioned within a shaft prior to inflation and to be inflated to contact the walls of the shaft to thereby seal the shaft and provide support to the shaft wall. A plurality of shaft plugs are adapted to by linked together in a manner to provide gas communication between the shaft plugs to provide a shaft plug to enable the shaft to be substantially filled by the shaft plug when inflated. Also defined is a method of sealing a mine shaft and supporting the shaft wall by use of a shaft plug.