Jerry Greenfield, left, and Bennett Cohen, the founders of Ben and Jerry's founders, in Burlington, Vt., in 1987. Toby Talbot / AP file

Jerry Greenfield, co-founder of the Ben & Jerry's ice cream brand, has stepped down from the company he started 47 years ago citing a retreat from its campaigning spirit under parent company Unilever.

Greenfield wrote in an open letter late Tuesday night -- shared on X by his co-founder Ben Cohen -- that he could no longer "in good conscience" remain an employee of the company and said the company had been "silenced."

He said the company's values and campaigning work on "peace, justice, and human rights" allowed it to be "more than just an ice cream company" and said the independence to pursue this was guaranteed when Anglo-Dutch packaged food giant Unilever bought the brand in 2000 for $326 million.

Cohen's statement didn't mention Israel's ongoing military operation in Gaza, but Ben & Jerry's has been outspoken on the treatment of Palestinians for years and in 2021 withdrew sales from Israeli settlements in what it called "Occupied Palestinian Territory."

Greenfield's resignation comes five months after Ben & Jerry's filed a lawsuit accusing Unilever of firing its chief executive, David Stever, over his support for the brand's political activism. In November last year Ben & Jerry's filed another lawsuit accusing Unilever of silencing its public statements in support of Palestinian refugees.

"It's profoundly disappointing to come to the conclusion that that independence, the very basis of our sale to Unilever, is gone," Greenfield said.

"And it's happening at a time when our country's current administration is attacking civil rights, voting rights, the rights of immigrants, women, and the LGBTQ community," he added.

Richard Goldstein, the then president of Unilever Foods North America, said in a statement after the sale in 2000 that Unilever was "in an ideal position to bring the Ben & Jerry's brand, values and socially responsible message to consumers worldwide."

But now Greenfield claims Ben & Jerry's "has been silenced, sidelined for fear of upsetting those in power." He said he would carry on campaigning on social justice issues outside the company.

The financial performance of the Ben & Jerry's brand isn't made public but Unilever's ice cream division made 8.3 billion Euros ($9.8 billion) in revenue in 2024. Unilever is in the process of spinning off its ice cream division, however, into a separate entity which involves cutting some 7,500 jobs across its brands globally.

Cohen and Greenfield founded the business in 1978 in Burlington, Vermont, where it is still based.

NBC News has contacted Unilever for comment overnight but had not received any at the time of publication.

Ben & Jerry's co-founder Jerry Greenfield resigns, claiming parent company Unilever 'silenced' its campaigning