Amazon employees in Germany have staged their first ever strikes, in a dispute over pay and benefits with the vast US online retailer.

Employees at two huge distribution warehouses, in Bad Hersfeld and Leipzig, launched the one-day strike, the giant services sector union Ver.di said.

Ver.di is demanding that Amazon's 9,000 workers in Germany be paid according to a wage deal in place for the retail and mail-order industries. The head of Amazon Germany, Ralf Kleber, rejected these demands, arguing that the retailer's staff were working in the logistics business, packing and dispatching parcels, rather than in the retail and mail-order sector.

Bad Hersfeld has a workforce of more than 3,000, while the Leipzig site employs around 2,000 people.

Amazon says it pays an hourly wage of €9.30 (£8) to employees in their first year, rising to €10 after that. Ver.di is demanding the minimum hourly retail wage of €10.66 for Leipzig; in Bad Hersfeld, the union wants staff to be paid the agreed sector rate, of just over €12 per hour, compared with the €9.83 Amazon currently offers.

Germany is a vital territory for Amazon. It is the retailer's biggest market in Europe, with sales last year reaching more than €6.5bn.

Workplace conditions for Amazon workers in Germany were recently highlighted by a TV documentary that accused the US group of hiring warehouse workers from crisis-hit countries such as Spain, and housing them in crowded hostels.

The TV programme alleged that employees were subjected to bullying from security personnel with neo-Nazi connections. Amazon said it did not tolerate discrimination or intimidation, and stopped using the security firm.