The landlocked central European country is part of Europe's visa-free Schengen zone, making it attractive to migrants coming through the Balkans. It has registered more than 80,000 migrants so far this year, nearly double the number in all of 2014.

Most are from poor or conflict-ridden countries like Syria, Afghanistan and Iraq, looking to move on to wealthier western Europe.

Hungary plans to complete a four-metre-high (12 feet) fence along its border with southern neighbour Serbia by November to stem the flow of migrants. The plan has drawn criticism from Serbia as well as the United Nations' refugee agency.

"There is a clear link between illegal migrants coming to Europe and the spread of terrorism," Orban said in an annual speech in Romania, where he usually outlines his political vision for the coming years.

"It is obvious that we simply cannot filter out hostile terrorists from this enormous crowd."

The issue of migration has become highly politicised in Hungary, with Orban's government mounting a billboard campaign telling migrants to respect Hungary's laws and stoking fears that foreigners could snatch the jobs of Hungarians.

"Our answer is clear: we would like to preserve Europe for Europeans ... and this also requires an effort from other (countries)," Orban said. "But there is something that we would not only like but we want: to preserve Hungary for Hungarians."

Illegal immigration had contributed to a rise in unemployment and crime in Western countries, he said.

Hungary's parliament has passed legislation, defying U.N. criticism, to shorten the time for screening asylum claims and to reject applications from migrants who have passed through third countries it considers safe without seeking asylum there.

Orban, whose Fidesz party is losing ground to Hungary's far-right, eurosceptic, anti-immigrant Jobbik party, said the "human rights fundamentalism" of the West provided moral encouragement to migrants.

European Union policies were not robust enough to defend its own citizens from the threats posed by rising immigration, he said.