Authorities in Greece have been carrying out a major clampdown on illegal immigration, with 500 undocumented migrants brought to a detention centre in Athens on Sunday.
Around 1,500 police officers were deployed in the capital alone at the start of the weekend. Media reports said another large-scale swoop was underway in the north-east of the country, along the border with Turkey.
Public Order Minister Nikos Dendias said on the radio that the operation was not a temporary measure and would continue.
The south-east European country has long been an illegal entry point to the European Union for migrants from Asia and Africa in particular, registering more than a million immigrants in the last decade. In 2010 alone the figure was 128,000, according to official data.