"So far, we have found out that there were four families from Iraq. None of the Iraqis has neither permission to enter the country, nor to reside in the Czech Republic. All of them are now in police custody, as well as the driver, who is a citizen of Romania," Katerina Rendlova, the spokeswoman for a unit of the Czech police dealing with foreigners, told reporters.
Numbers of undocumented migrants trying to cross the Czech Republic to reach Germany and other Western countries have significantly increased since June 2015.
Illegal migration peaked at 1,767 in August and declined in October-November to about 500 people.
The Czech Republic tightened controls on foreign residents in June. Law enforcement officials have conducted regular interstate train and bus inspections since then, and extended controls across 20 crossings along the Austrian border.