Greece will open four migrant registration centers in time for an EU summit this week, a government source told AFP Monday, as Athens comes under heavy pressure to control the massive influx to Europe.

Four of Greece's five "hotspot" centers will formally open by Wednesday on the islands of Lesbos, Chios, Leros and Samos, which have been struggling to cope with the arrival of hundreds of thousands of migrants landing from Turkey in flimsy boats, the source said.