WARSAW, Poland -- Ahead of Christmas, popular U.S. online retailer Amazon has opened three logistics centres in western Poland, completing a network that covers the European market.

A centre employing some 2,500 workers opened on Wednesday in Sady, near Poznan. Two others, jointly employing some 2,500 people were opened Tuesday near Wroclaw. Built at the costs of 100 million euros each, they are Amazon's only centres in Central and Eastern Europe.

To ensure smooth operation through the Christmas shopping season, they will be temporarily reinforced with another 5,000 workers.

Tim Collins, director for operations in Europe, said the centres are part of a broader network covering Europe. Amazon also has logistics centres in Germany, Britain, France and Italy.