"Hills and mountainous areas account for 21% of Croatian territory, while in Europe they make up 17% of the territory," Zmajlovic said in the statement.
The press release recalls that this year's theme of International Mountain Day is "Mountains: Key to a Sustainable Future".
International Mountain Day, held each year on 11 December, was established by the UN General Assembly in 2002 to encourage events to be organized at all levels that day to promote sustainable development in mountains.
This year, the Croatian national park Northern Velebit and the nature parks Velebit, Biokovo, Papuk and Ucka held various events to raise awareness among citizens of the importance of mountains.
The other two national parks in Croatian mountainous areas are Risnjak and Paklenica, and the other two nature parks in mountainous areas are Zumberak and Medvednica.