Germany's Foreign Minister Frank-Walter Steinmeier is seeking to ease tensions with Poland, following a public exchange of insults and media barbs that have enflamed politicians and editors in both countries.

Steinmeier said Wednesday that both governments have a responsibility to ensure friendly relations.

Friction was evident last week at a European Union summit, when Polish leaders repeatedly rejected German lobbying efforts on behalf of a new European Union treaty, before finally agreeing to a last-minute compromise.

Ahead of the summit, Polish Prime Minister Jaroslaw Kaczynski argued that Poland deserved more EU voting power, because its population would be far larger now if it had not been decimated by Nazi Germany in World War II.

Tuesday, a Polish magazine, Wprost carried a depiction of a bare-breasted German Chancellor Angela Merkel smiling along with child-like images of Mr. Kaczynski and his twin brother, Polish President Lech Kaczynski.

The picture carried the caption "Europe's Step-Mother," and generated outrage in many German newspapers. The Cologne daily Kolner Stadt-Anzeiger said the picture mocked and ridiculed Chancellor Merkel. A number of German politicians termed the photo tasteless and called for a Polish apology.

Some information for this report was provided by AFP and Reuters.