The declaration was at a meeting of South-East European Cooperation Process (SEECP) member-states in the Greek city of Loutraki on Wednesday.
Croatian Justice Minister Vesna Skare-Ozbolt presented measures being taken by Zagreb to fight organised crime, corruption and terrorism.
Skare-Ozbolt said that Croatia, which had opened membership talks with the European Union, supported cooperation in the region and was taking active part in the regional initiatives such as SEECP, SEEPAG (South European Public Prosecutors Advisory Group) or SECI (Southeast European Cooperation Initiative).
The Special Co-ordinator of the Stability Pact for Southeast Europe, Erhard Busek, who also attended the Loutraki event, pointed out the importance of cross-border cooperation.
Greece is currently the SEECP chair, and Croatia will take over the chairmanship of this regional initiative in May.
In addition to Greece and Croatia, SEECP members are Albania, Bosnia-Herzegovina, Bulgaria, Macedonia, Moldova, Romania and Serbia-Montenegro.