A hydraulic tool for use with a clamp connector where a first clamping element and a second clamping element of the clamp connector are pivotable towards each other into a closed position by exerting a pulling force on an operating shaft and a pushing force on a spacer sleeve, and where said first and second clamping elements are lockable in said closed position by tightening a locking nut against a shoulder on the spacer sleeve. The tool includes a pulling element; a hydraulic power unit for moving the pulling element in relation to the spacer sleeve and thereby allow the hydraulic tool to exert a pulling force on the operating shaft and a pushing force on the spacer sleeve; a rotatable actuating member with a socket engageable with the locking nut; and a drive motor for rotating the actuating member to allow the actuating member to rotate the locking nut.