Germany is Amazon's second-biggest market behind the United States and sales there grew almost 21 percent in 2012 to $8.7 billion, a third of its overseas total. Amazon took its most daily orders in Germany last December 16, when almost 4 million articles were bought, with shipments peaking on December 17.

Amazon, which employs 9,000 warehouse staff in Germany plus 14,000 seasonal workers at nine distribution centers, said 1,115 staff had joined the strike at three sites, but there had been no delays to deliveries.

"Our customers can continue to rely on us for the prompt delivery of their Christmas presents," a spokeswoman said, adding that Amazon uses its whole European logistics network over the Christmas period to ensure delivery times.

The Verdi union said up to 700 workers joined the strike in Amazon's logistic center in Bad Hersfeld, plus 500 to 600 in Leipzig. For the first time, the union also called a strike in Graben, where Verdi said 600 workers took part.

"The Amazon system is characterized by low wages, permanent performance pressure and short-term contracts," Verdi board member Stefanie Nutzenberger said in a statement.

GLOBAL AGREEMENT

A delegation of German workers was due to rally at Amazon's headquarters in Seattle along with U.S. unions. In addition, workers in Amazon's center in the German town of Werne will protest on Tuesday, while strikes are expected to continue all week in Leipzig and until Wednesday in Bad Hersfeld.

"Amazon must realize it cannot export its anti-union labor model to European shores. We call on the company to come to the table and sign a global agreement that guarantees the rights of workers," said Philip Jennings of global trade union UNI.

Verdi has organized several short stoppages this year to try to force Amazon to accept collective bargaining agreements in the mail order and retail industry as benchmarks for workers' pay at Amazon's German distribution centers.

But Amazon's German country head Ralf Kleber said the company would not bow to pressure from striking workers and was more worried about bad weather hurting Christmas deliveries, he told Reuters in an interview last month.

Kleber said Amazon pays warehouse workers well according to the standards of the logistics industry, starting at 9.55 euros ($13.11) an hour, and does not think the more generous terms of the mail order and retail sector are justified.

Amazon has recently announced it would build three new logistics centers in Poland and two in the Czech Republic, prompting speculation that it could seek to shift work across the border from strike-hit centers in Germany.

But Kleber said Amazon expected to keep expanding in Germany, including eventually delivering fresh groceries too.

($1 = 0.7283 euros)