BERLIN (Reuters) - A German lobby group has bowed to pressure from Poland and withdrawn the nomination of a conservative to oversee a new museum that will show the plight of Germans forced out of eastern Europe after World War Two.

The League of Expellees' nomination of Erika Steinbach to sit on the museum's board had caused outrage in Poland, where her forceful promotion of the interests of millions of Germans expelled from eastern Europe after the war is controversial.

The subject of the 12.5 million Germans expelled from Poland, Hungary and Czechoslovakia after the Nazi defeat has strained relations between Germany and Poland ever since the war, in which 6 million Poles died.

Many Poles fear the new museum, which will focus on the fate of expelled Germans but will also refer to other European expulsions, will portray Germans as victims of a war they began.

Steinbach's withdrawal will come as a relief to German Chancellor Angela Merkel who was under pressure from fellow conservatives to back Steinbach for the post and from Warsaw to drop her.

"We want to resolve a blockade that wasn't caused by us," the League said in a statement.

"For this reason, and this reason alone, the League's executive committee has accepted its president's request not to nominate her to the committee (charged with overseeing the museum) for the time being."

After the war, Poland's borders were shifted west by international treaty and German communities were forced to leave homes in Poland, Hungary and what was then Czechoslovakia.

Polish Prime Minister Donald Tusk visited Germany last week and urged Merkel to drop Steinbach. The leading post at the Berlin museum required the approval by Merkel's cabinet.

Steinbach's withdrawal could still cause a backlash among some supporters of Merkel's conservatives who have grown annoyed at the chancellor's shift towards more leftist policies and compromises with her Social Democrat (SPD) coalition partners.

Merkel faces a federal election in September. Her challenger, SPD Foreign Minister Frank-Walter Steinmeier, had seized on the museum row, urging her to make a quick decision.

In an act of protest, the League did not name a new candidate for the museum, saying it would not let its choice be dictated by the SPD or anyone else.