A wellbore valve assembly including a valve member which is moveable relative to the valve seat, the valve assembly being receivable in a wellbore tubing having a first end and a second end, the valve member being moveable between an open position relative to the valve seat, and a position in which the valve member is seated against the valve seat, the valve assembly including a valve member biasing device for biasing the valve member towards the open position, the valve member being operable to close in the event of a force which exceeds a predetermined value being applied in either direction relative to the direction in which the valve member biasing device acts.