The British government is seeking the extradition of three suspected dissident republicans arrested in Slovika.
A spokesman for the Northern Ireland Office told ireland.comthat the Irish men were arrested on "the expectation of an extradition application from the UK". He added Slovika and Britain have a partnership agreement for extradition.
Dissident republicans, namely the Real IRA, have been blamed for attacks on RUC and British Army bases in Northern Ireland and in England, including a rocket attack on MI6 headquarters in London.
Previously seized Real IRA weapons have been shown to have originated in the Balkans.