Migrant crisis: Lesbos camp clashes as Greek minister visits
Clashes have broken out between police and stone-throwing migrants at a detention centre on the Greek island of Lesbos, police said.
Images posted on social media showed burning rubbish and parts of the Moria camp being evacuated.
The unrest came during a visit by the Greek migration minister and a Dutch minister.
The migrants are angry about the detention conditions and an EU deal to return economic migrants to Turkey.
Moria camp was visited by the Pope earlier this month.
The unaccompanied minors section of the camp was particularly affected by the unrest, AFP news agency reported.
About 3,000 people are being held in Moria, waiting to hear what will happen to them.
A spokesman for the UN refugee agency said the migrants were "angry and frustrated" and there had been a "surge in violence" in recent days.
Moria was turned into a closed detention centre after the deportation deal was announced.
Under the EU-Turkey agreement, migrants who have arrived illegally in Greece since 20 March are to be sent back to Turkey if they do not apply for asylum or if their claim is rejected.
For each Syrian migrant returned to Turkey, the EU is to take in another Syrian who has made a legitimate request.
Earlier, 49 migrants from Afghanistan, Iran, Pakistan and Myanmar became the third group of migrants to be returned to Turkey under the deal.