Berlin  - German dairy farmers used their tractors to blockade milk-processing plants in several states Monday, a week after protests at low milk prices began.

The blockade came after weekend talks between dairy farmers and the milk-processing industry broke down in Berlin Sunday night.

Speaking outside a large milk-processing plant in the state of Rhineland-Palatinate, the head of the local dairy farmers, Oliver Grommes said, "There's no milk going in and no milk coming out at the moment."

Grommes said the protests would continue until farmers had secured their goal of a farm-gate price of 43 cents (67 US cents) a litre, compared with current prices between
27 and 35 cents.

"We want to increase the pressure," Grommes said ahead of a meeting between dairy farmers and food retailers.

The protest, which has seen farmers pour milk away or feed milk intended for human consumption to other animals, has caused shortages in some supermarkets and provoked outrage from many commentators.

Cheese plants have cut output.

The German dairy farmers have sought and received backing from farmers in neighbouring countries after the industry said it would go abroad to source fresh supplies.

However, Germany's national farmers' union does not support the boycott, contending that the European Union should export more milk. (dpa)