The European Union has formally invited Slovakia to join the euro zone on Jan. 1, 2009.

Diplomats say EU finance ministers have agreed on an exchange rate of 30.1260 Slovak korunas for euro1.

EU Monetary Affairs Commissioner Joaquin Almunia says Tuesday’s approval is proof of the “great success” of Europe’s monetary union.

Slovakia will become the 16th country to adopt the euro. It is the second of eight Eastern European nations that joined the EU in 2004 to use the single currency.