We propose a novel control approach for cooperative dual-arm manipulation tasks. Our scheme has three typical features: (1) the task performed by two robots is represented as a motion of a virtual mechanism and the task execution is accomplished by controlling the virtual mechanism; (2) the two arms and the task form a joined kinematic chain; (3) the scheme allows a cooperative dual-arm system to perform the task also when robot base is moving. The calculation of the Jacobian matrix of a chained two-arm mechanisms is based on a methodology which is using the Jacobian matrices of particular robot mechanisms and their end-effector positions and orientations. The proposed algorithm for dual-arm manipulation is verified by simulations of two cooperating planar robots and by experiments on a dual-arm robot consisting of two KUKA LWR arms.