European Union finance ministers have told new member-states hoping to adopt the euro that the currency must be spelt "euro" on notes, coins and all legal documents.

The ruling will affect three countries: Lithuania, where the currency is called "euras"; Latvia, where it is "eiro"; and Slovenia, where it is "evro".

The ECB President, Mr Jean-Claude Trichet, said that it had already been agreed in 1997 that the euro should be spelt in the same way throughout the EU - apart from Greece, which has a different alphabet. "The fact that, having a single currency, we have the same spelling... seems to be frankly natural," he said.

The ruling could create a particular difficulty in Lithuania, where a State Language Board must approve the adoption of all new words into Lithuanian.

Mr Trichet said that the ECB did not prescribe the plural form of the word euro but he told The Irish Times that the most commonly accepted form in English is "euro", as opposed to "euros".