At least four people were hurt in a night of clashes on Sunday between migrants at a reception center in Langadikia, near Thessaloniki in northern Greece.
Local media report that groups of Kurds and Algerians fought pitched battles inside the center before riot police intervened.
Facilities were damaged and five migrants were arrested.
Clashes are common within Greece’s overcrowded reception centers.
Last December, at least 10 people were injured during clashes between refugees at the Moria camp on the Greek island of Lesvos.
The government has expressed alarm over the increased flow of migrants and refugees in the last few months.
Three hundred and fifty undocumented migrants landed on the islands of Lesvos and Chios on Sunday, only days after Lesvos residents protested against the overcrowded registration facilities.
At the same time, Greek authorities expressed concern over the rapidly rising number of undocumented migrants crossing the land border with Turkey in the Evros region.