Prague (AFP) - Thousands of people protested against migrants in towns around the Czech Republic on Wednesday, a week after the UN slammed the country's treatment of new arrivals as "degrading".

Up to 5,000 people took to the streets in Prague and four other towns on the country's national day. In the capital, riot police intervened to separate anti-migrant protesters from around a hundred people staging a counter-demonstration.

Lutz Bachmann, the founder of Germany's anti-Islam PEGIDA movement, was among the speakers to address the crowd in Prague.

More than 700,000 migrants have arrived in Europe this year, most from Syria, Iraq and Afghanistan, in the continent's worst refugee crisis since World War II.

The influx has caused tensions between EU members and given a boost to far-fight anti-immigration groups across the continent.

Czech President Milos Zeman has come under fire for his fiery anti-migrant broadsides, earning sharp criticism from the UN's human rights chief Zeid Ra'ad Al Hussein, who has also accused Prague of systematically detaining migrants in "degrading" conditions to deter others from entering the country.