WASHINGTON (Reuters) - Donald Trump Jr. sought on Thursday to clarify his remark that the media would be “warming up the gas chamber” if the Republican Party behaved the same way as the Democrats during the U.S. presidential campaign, saying it was a reference to capital punishment, not the Nazi-led Holocaust.

Donald Trump Jr speaks on the second day of the Republican National Convention in Cleveland, Ohio, U.S. July 19, 2016. REUTERS/Aaron Josefczyk

Trump, the son of Republican presidential nominee Donald Trump, spoke to NBC News after the Anti-Defamation League, which combats anti-Semitism, asked him to retract his statement.

“Trivialization of the Holocaust and gas chambers is NEVER okay,” the Anti-Defamation League tweeted.

John Podesta, the chair of Democratic presidential nominee Hillary Clinton’s campaign, told reporters on a call that the wording of Trump’s remark was “extremely insensitive, divisive and probably pretty consistent with the kind of rhetoric he heard around the house when he was growing up.”

“I think it’s never acceptable to use language like that,” Podesta added.

Nazis used gas chambers during World War Two to kill millions of Jews imprisoned in European concentration camps.

Trump made the “gas chamber” remark during an interview with a Philadelphia radio station on Thursday morning to explain how the media would react if the Republican Party had intervened in the nominating contest the way the Democratic Party has been accused of doing to benefit Clinton over former party rival U.S. Senator Bernie Sanders.

“Without the media, this wouldn’t even be a contest, but the media has built her up, they’ve let her slide on every discrepancy, on every lie, on every DNC game, trying to get Bernie Sanders out of the thing,” Trump said.

“If Republicans were doing that, they’d be warming up the gas chamber right now,” the nominee’s son added.

Trump’s campaign said the uproar over the comment was another example of bias among the media covering the presidential campaign.

“Don Jr. was clearly referring to capital punishment to make the case that the media continues to take words out of context in order to serve as the propaganda arm of the Hillary Clinton campaign,” Trump spokesman Jason Miller said in an email.