Greece's hardline migration minister, Thanos Plevris, threatened unspecified "very harsh" measures against asylum seekers should heavy migratory flows continue in small boats from north Africa to Crete.
The southern Greek island has emerged as the prime destination in Greece for people from the Middle East, the Indian subcontinent and Africa seeking a better life in the European Union.
So far this year, almost half the roughly 10,000 people to have entered Greece by land and sea arrived on Crete - traveling from Tobruk in eastern Libya.
Some 600 people made landfall on Thursday.
"Until [Thursday] we were at the same numbers as last year," Plevris said.
