Hamburg - About 200 Syrian and Afghan refugees clashed in a crowded German refugee centre in Hamburg overnight, leaving several people injured in the third such riot this week, police said on Thursday.
Fifty police were called in to contain the mass brawl, which broke out in an argument in a shower block, local newspaper the Morgenpost reported.
The two groups attacked each other with iron bars and furniture and by hurling rocks, reported the daily and DPA news agency, citing emergency personnel in the northern river port city.
Police said several people were wounded, and several arrested, without providing figures.
Germany is Europe's top destination for people fleeing war and misery from conflict zones and poverty-stricken countries and expects up to one million newcomers this year.
Aid workers warn that tensions easily flare as often traumatised refugees, mostly men, share crowded spaces while lacking common languages to defuse everyday conflicts.
The centre in Hamburg, located in a large building that formerly housed a hardware store, is now home to 800 people, with more recent arrivals sleeping on mattresses outside.
In earlier disturbances in Germany this week, 14 people were injured Sunday in a centre in the central city of Kassel when 70 Pakistanis clashed with 300 Albanians.
On Tuesday, dozens of Syrians and Pakistanis came to blows in a refugee shelter in the eastern city of Dresden.
According to southern Bavaria state, the main entry point for migrants to Germany, up to 280 000 asylum seekers arrived in Germany in September alone, topping last year's total.