ZAGREB, Croatia (AP) — The U.S. Embassy in Croatia on Monday strongly denounced a march by far-right nationalists in the Croatian capital of Zagreb who also waved an American flag and reportedly voiced support for President Donald Trump.

The embassy said in a statement it "rejects, in the strongest terms, neo-Nazi and pro-Ustasha views expressed during the demonstration of a few people in Zagreb on Sunday."

The protesters, dressed in black and chanting slogans used by Croatia's pro-Nazi World War II Ustasha regime, are members of the small, far-right A-HSP party which is not represented in the country's parliament. As they marched through the center of the city, they waved an American flag, as well as the flags of Croatia and the far-right German NPD party.

The Ustashas killed tens of thousands Jews, Serbs, Gypsies and anti-Nazi Croats in concentration camps during World War II.

"We condemn any attempt to link the United States to this hateful ideology," the U.S. Embassy said. "Such a suggestion is an affront to the memories of the 186,000 U.S. soldiers who died in Europe fighting Nazi Germany and the many millions of innocent victims killed during World War II."

Police arrested the leader of the extremist A-HSP party after the protest, whose participants also called for the expulsion of "all enemies" from Croatia and its departure from the 28-nation European Union.

Croatia is facing a rise in far-right sentiments, especially against minority Serbs who remained in the country after a war between the two neighbors in the 1990s during the bloody breakup of Yugoslavia.

Stickers featuring a drawing of a "Serbian family tree" showing people hanging from its branches appeared over the weekend in Croatia's border town of Vukovar.

Croatia's government has condemned both the far-right march and the stickers, saying they are "offensive and shameful."