BERLIN — The nationalist Alternative for Germany party's co-leader said Monday he "regrets" the impression created by remarks in which he dismissed the Nazi era as "speck of bird poop" in German history, which drew condemnation across the mainstream political spectrum.

Alexander Gauland told a gathering of the party's youth wing on Saturday that Germans must take responsibility for 12 years of Nazi rule but argued that "Hitler and the Nazis are just a speck of bird poop in more than 1,000 years of successful German history."

Gauland's comments were defended by many in the party, known by its German acronym AfD, which entered the national parliament in last year's election on anti-migrant and anti-establishment sentiment and is now the biggest opposition party.

But there were some dissenting voices. A group representing party moderates, the Alternative Center, said in a statement late Sunday that Gauland's comment sounded at best ambiguous and "this should not happen to a politician who has a minimum of instinct and sense of responsibility for our history." It called for a public apology.

On Monday, Gauland asserted in a statement that he had used the words "bird poop" to express his "deepest contempt for Nazism."

He said that "many saw the expression as an inappropriate trivialization" but "nothing could be further from me than to allow such an impression to arise."

"I regret the resulting impression," he added. "It was never my intention to trivialize or deride the victims of this criminal system."

Chancellor Angela Merkel's spokesman, Steffen Seibert, said Monday "it is shameful that we have to deal with such comments by a lawmaker in parliament" and that the government strongly rejects any downplaying of the Nazi era.

The general secretary of Chancellor Angela Merkel's party, Annegret Kramp-Karrenbauer, has argued that Gauland's comments reveal the true nature of a party hiding behind middle-class respectability.

Last year, prominent AfD member Bjoern Hoecke said Germany needs to perform a "180-degree turn" when it comes to remembering its past, and said the Berlin memorial to the millions of Jews killed in the Holocaust is a "monument of shame." And before last year's election, the 77-year-old Gauland said the country has a right to be "proud of German soldiers' achievements in two world wars."

Also Monday, AfD's leadership issued a statement expressing its disapproval of the singing by delegates at Saturday's youth wing meeting of the entire German national anthem — including the verse which begins with "Deutschland, Deutschland ueber alles" that was dropped after the Nazis' defeat.

Damian Lohr, the youth wing's leader, said he "takes note" of the criticism but argued that singing the verse isn't banned and that the hymn was "abused by the Nazis."