Border controls introduced this week by Czech and Austrian authorities at borders with Slovakia have netted hundreds of arrests of suspected illegal migrants and alleged human smugglers.

Both countries say the measures are necessary due to the drastic increase in illegal migration this year from Syrians crossing European Union (EU) borders.

On remote muddy roads, away from the eyes of the police, groups of Syrian immigrants hide on the Slovak side of the Moravia River.

They've traveled thousands of miles to reach the border with Czechia, where authorities this week stepped up controls to curb the rise of illegal immigration.

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We spotted a group of three Syrian men and two children who had attempted to cross into Czechia, only to be turned back.

Omar, who fled his home near Damascus, the Syrian capital, told CGTN Europe they had been traveling for nearly two months across "Syria, Turkey, Greek, Serbia, Macedonia, and Magyar (Hungary)."

Czech authorities say illegal immigration at their border has shot up by 1,200 percent since the beginning of the year. They have implemented controls at 27 border crossings with Slovakia.

Police at border checkpoints have found immigrants hiding in the trunks of cars and trucks. They say most are Syrian men, but they've also detained women and children.

Czech police say that eight hours after setting controls at the border with Slovakia, they had arrested 120 immigrants that crossed illegally into the country. They've also detained nine people suspected of human smuggling.

In the South Moravia region in Czechia, police are also focusing on identifying and arresting suspected human smugglers.

"This morning, our officers detained eight human traffickers," said Petr Vala of the South Moravia police department. "They attempted to smuggle nearly 80 immigrants into our territories using several vehicles."

Some suspected smugglers have been driving the migrants while under the influence of drugs, said the police.

Austrian authorities have also stepped up checks at the border with Slovakia to curb illegal migration.

Austria, Czechia and Slovakia belong to the EU's visa-free Schengen zone, where residents of those nations can travel across borders without showing passports or visas.

Away from the border, migrants can still be stopped. Czech police have detained Syrian immigrants along the highway to Prague and at this train station in Breclav as they journey on to other European countries.

We asked the group of Syrian migrants we encountered where they were headed and they unanimously replied: "Alemania, Alemania (Germany, Germany)."

The Slovak government has criticized Austria and Czechia for the increased border measures, saying they run counter to EU legislation.

Despite increased patrols, many remain undeterred.

This group of immigrants said they would wait for nightfall along the banks of the Moravia river to attempt to cross again.