ATHENS, Greece (AP) — A little-known extreme right-wing group has claimed responsibility for an arson attack on an Afghan community center in central Athens that caused significant damage, but no injuries.

A group calling itself Krypteia claimed responsibility in a call to a Greek news website on Friday.

Authorities say they think the assailants started the fire by pouring flammable liquid on the door of the Afghan community center, which is located on the fifth floor of an Athens building. Flames spread inside, damaging desks, tables and computers on Thursday afternoon.

The United Nations refugee agency condemned the attack, saying the center had been "full of people, including children, not long before" the arson.

The U.N. agency called for steps to protect refugees and migrants.