Employees at four of Amazon's distribution centres in Germany have staged a co-ordinated strike after the company refused to hold wage talks.
An estimated 2,000 members of staff did not show up for work earlier this week in an attempt to persuade the firm to accept an agreement in line with other retailers.
Amazon claimed that the numbers of employees taking part was not large enough to disrupt the firm's deliveries.
''Less than 600 employees of the early shift have followed the call to strike action,'' a spokeswoman for Amazon said in an email. ''Therefore the strike will not impede on the compliance with Amazon's delivery promise.''
The dispute hinges on the retail and service workers union Ver.di, which wants Amazon to declare itself as a retailer, leaving it subject to labour laws that require wages to be set through collective bargaining.
Amazon has countered with the claim that its warehouses are logistics centres rather than shops - and that their staff receive wages towards the upper end of the logistics pay range.
Ver.di has been fighting the case since spring 2013, but the action this week was the first strike to be held simultaneously at the four warehouses: Bad Hersfeld, Leipzig, Graben and Rheinberg.
Amazon has agreed to increase wages by 2.1 to three per cent in the Graben distribution centre, but the union has confirmed it will continue to take action against the web giant.
''The workers are demanding their right to a collective bargaining agreement and fair labour conditions,'' said Stefanie Nutzenberger, a Ver.di member.
Amazon is also currently fighting a price dispute with the German branch of the Bonnier publishing group over e-book pricing. Similar to its clash with French publisher Hachette, the firm has been accused of breaching regulations that prevent retailers from offering discounts on printed books.
If Amazon continues to disregard the ruling, it could face a fine of up to 250,000 euros (£197,000).