The nationalist Alternative for Germany party’s co-leader has said he “regrets” the impression created by remarks in which he dismissed the Nazi era as a “speck of bird poop” in German history.

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”.

Mr 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.

It was never my intention to trivialise or deride the victims of this criminal systemAlexander Gauland, Alternative for Germany

But there were some dissenting voices: a group representing party moderates, the Alternative Centre, said in a statement late on Sunday that Mr 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, Mr 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 trivialisation” 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 trivialise or deride the victims of this criminal system.”

It is shameful that we have to deal with such comments by a lawmaker in parliamentAngela Merkel's spokesman

Chancellor Angela Merkel’s spokesman Steffen Seibert said “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 Mrs Merkel’s party, Annegret Kramp-Karrenbauer, has argued that Mr 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, 77-year-old Mr Gauland said the country has a right to be “proud of German soldiers’ achievements in two world wars”.

AfD’s leadership also issued a statement on Monday 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 is not banned and that the hymn was “abused by the Nazis”.

PA Media