The European Union's population grew by 2.3 million in 2004, mostly due to immigration which accounted for 1.9 million of the total, the bloc's statistical agency Eurostat said on Tuesday.

The 25-nation EU's population was estimated at 459.5 million on January 1, 2005, up from 457.2 million a year earlier, Eurostat said in a statement.

Copyright Reuters, 2005