Hungary began building a temporary fence on the border to Croatia early Friday, Prime Minister Viktor Orban announced, and several hundred Hungarian police officers and soldiers were sent to the Hungarian-Croatian border, according to the Hungarian news agency MTI.

He told Radio Kossuth that the fence will be a long 41 kilometer and the "preliminary line of defense" will be completed during the day.

"We must take the same measures we have taken along the Serbian-Hungarian border," he said.

All efforts must be directed at halting illegal migration and this "business chain" has to be interrupted, Orban said, speaking of what Europe must do.

"We know who organized an attack on Hungary from the territory of Serbia," Orban said, adding that the Hungarian forces had already arrested a "terrorist".