ATHENS (Reuters) - A group of Syrian refugees protested on Wednesday at the European Asylum Support Office (EASO) premises in a migrant camp on the Greek island of Chios, forcing its staff to evacuate, officials said.

It was the second protest by asylum seekers this week against delays in the processing of their claims. On Monday, a group on the island of Lesbos hurled rocks and burning blankets at an EASO office, damaging three of its containers.

Tensions have boiled over in overcrowded migrant camps on Greece's islands, hosting about 15,000 asylum seekers. A European Union deal with Turkey prevents them from going beyond Greece, or even its islands, until their claims are assessed. Those who do not qualify are deported to Turkey.

A police spokesman for the northern Aegean region said minor damage was caused to EASO's offices on Chios during Wednesday's protest. Riot police stepped in to break up the crowd, he said.

EASO Spokesman Jean-Pierre Schembri said the agency's 30 staff had to evacuate the camp, suspending interviews. Work has yet to resume on Lesbos following Monday's attack, he said.

More than 60,000 refugees and migrants are stranded in Greece since March, when Balkan countries closed their borders and intercepted their journey to northern Europe.

(Reporting by Karolina Tagaris; Editing by Angus MacSwan)