Human rights activists and lawyers have condemned police in the Czech Republic for writing numbers on the arms of migrants after detaining them.

Officers used pens to mark 214 refugees, mostly Syrians, who were detained on a train yesterday at a border crossing from Austria and Hungary.

The measure has provoked anger because it recalls Nazi Germany's practice of writing numbers on concentration camp prisoners.

The controversy came as thousands of desperate migrants staged angry protests outside Budapest's main international railway station today after Hungarian authorities refused to let them board trains bound for Western Europe.