The 12 euro zone countries are Austria, Belgium, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Portugal and Spain.

They have a combined population of 304 million people, and a gross domestic product of around 7 billion euros (£5.5 billion).

Three European Union members have not yet joined the euro zone: Britain, Denmark and Sweden. Andorra, Monaco, San Marino and the Holy See (Vatican City) will also adopt the euro, and it will be the official currency in the Yugoslav republic of Montenegro and the southern Yugoslav province of Kosovo. French overseas departments will also adopt the euro but overseas territories such as French Polynesia, Wallis and Fortuna, and New Caledonia will continue to use the Pacific franc.