THE London-listed base metals group Billiton plc has confirmed that it has offered shareholders of Rio Algom Limited CD27 (Canadian dollars), or R129,87 a share, in pursuit of its bid for the Canadian zinc and copper producer. Billiton said the company had posted the offer to shareholders on Friday. Billiton is competing for the stake against Canadian group Noranda, whose earlier CD24,50 (R118,74) offer has already been rebuffed by Rio Algom shareholders. “Billiton will monitor developments, but does not intend to comment unless and until an offer above CD27 per share is made to Rio Algom shareholders,” the company said.