The Slovak and Polish border police must further cooperate to fight against illegal immigration after joining the Europe's passport-free Schengen zone, the two countries' interior ministers said on Thursday.

"Illegal migration will not cease threatening us after our entry into the Schengen zone," Slovak Interior Minister Robert Kalinak said after meeting with his Polish counterpart Ludwik Dorn.

Both ministers said that Slovakia and Poland would have to exchange information on the border regime transformation.

Kalinak praised the cooperation between the two countries' police forces in the past.

"Polish colleagues have helped us with the extradition of culprits to Slovakia in some criminal cases," Kalinak said.

Dorn added that the interior ministers' task would also include improving infrastructure at border crossings where checks would be abolished after both countries' entry into the Schengen system.

Slovakia, Poland and other new member states of the European Union (EU) originally planned to join the 15-nation Schengen zone in October 2007. However, the EU considered postponing the Schengen enlargement until October 2008 due to problems with expansion of the Schengen zone central data base.

The Schengen Agreement allows people who are legally present in European countries that are parties to the Agreement to travel freely without having to show passports when crossing interior frontiers. The term Schengen Agreement comes from the name of the village Schengen in Luxembourg where the agreement was signed in 1985.

Source: Xinhua