Polish President Andrzej Duda has reiterated his warning to Germany over the controversial Nord Stream 2 pipeline designed to transport Russian gas to Europe.

The construction "should not be carried out," Duda told reporters after meeting President Frank-Walter Steinmeier in the morning.

It would threaten the energy supplies of eastern and central European countries, he said, adding that Warsaw had expected more solidarity from the EU over what he regarded as a strategic political decision.

Steinmeier countered that the purchase of natural gas was a financial decision rather than a political one.

Warsaw also sees a risk that the gas pipeline will make Europe too dependent on Russia for its energy needs. Poland - which lies between Germany and Russia - is not involved in the construction of the pipeline, which runs under the Baltic Sea.

Duda is set to continue his visit by holding talks with Chancellor Angela Merkel in the afternoon.

Tensions between Poland and the EU over refugee quotas and a long-running dispute over the forced retirement of some top judges are likely to figure in the bilateral talks.

In November, Merkel and her cabinet are scheduled to travel to Poland for German-Polish government consultations.