Opinion of the European Central Bank of 5 July 2007 at the request of the Council of the European Union on a proposal for a Council regulation amending Regulation (EC) No 974/98 as regards the introduction of the euro in Cyprus, on a proposal for a Council regulation amending Regulation (EC) No 974/98 as regards the introduction of the euro in Malta, on a proposal for a Council regulation amending Regulation (EC) No 2866/98 as regards the conversion rate to the euro for Cyprus and on a proposal for a Counci