Riot police fired stun grenades yesterday at dozens of migrants, who threw stones and set bins on fire before order was restored at the Oreokastro camp near Thessaloniki in northern Greece, a police source told AFP.
The protest broke out in the evening after the woman, 35, and her son, 10, both Syrian Kurds, were apparently killed in an accident involving a passing car, which was then torched in the protest.
The car's elderly Greek driver was arrested.
Last month, a seven-year-old girl from Syria was killed by a car in a similar incident outside a refugee camp near the town of Katerini.
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Her mother and sister who was a year older were also hurt at the time.
There are over 60,000 refugees and migrants trapped in Greece, most of them Syrians fleeing war who are waiting for asylum approval or relocation elsewhere in the European Union.
But that procedure has been held up by the reluctance of many EU states to accept Muslim refugees after a spate of jihadist attacks in Belgium, France and Germany.