Immigration flows to Greece surged to 48,000 in the five days to Oct. 21, the highest weekly total so far this year, bringing the number of Mediterranean migrant arrivals in Europe to 681,000 the International Organization for Migration said on Friday.

Amin Awad, the Middle East director for the U.N. refugee agency UNHCR, said Russian airstrikes and increased fighting around the Syrian city of Aleppo had contributed to the "dynamic of displacement", with about 50,000 displaced, but had not contributed much to the refugee exodus.