(CNN)The editor of a British food publication has resigned after joking in an email about "killing vegans" and force-feeding them meat.
William Sitwell, who edited the magazine produced by upmarket supermarket chain Waitrose, was responding to a pitch from freelance journalist Selene Nelson about a series of features covering vegan cooking.
"How about a series on killing vegans, one by one," Sitwell replied. "Ways to trap them? How to interrogate them properly? Expose their hypocrisy? Force-feed them meat? Make them eat steak and drink red wine?" he added.
His comments were met with a furious backlash online, where internet users called the editor "out of touch" and threatened to boycott Waitrose.
"Does this aggressive, ignorant and moronic behaviour represent Waitrose?" one Twitter user asked, while another wrote: "You have lost my custom until this dullard is sacked."
Waitrose became the first major British supermarket to launch a fully vegan range in June, and reported last month that its sales of vegan-based products were up 85% compared to last year.
"William's email absolutely doesn't represent our views about vegans and vegan food," the company said on Twitter after confirming his departure.
Sitwell joined Waitrose Food magazine in 1999, and also appears on BBC television cooking program "MasterChef."
"This editor's sin -- far worse than proposing 'killing vegans' -- is being completely OUT OF TOUCH with the British public," Ben Williamson, senior international media director at animal rights group PETA, wrote on Twitter in response to the controversy.
Around 600,000 people in the United Kingdom are vegans, according to British charity The Vegan Society.
"I'm certainly interested in exploring why just the mention of veganism seems to make some people so hostile," food journalist Nelson wrote in response to Sitwell's original email. "It sounds like you have some opinions on this?"
In a post on Instagram, Sitwell apologized "to any food and life-loving vegan who was genuinely offended by remarks written by me."
He called the comments "an ill-judged joke in a private email," and noted that the magazine devoted an entire issue to vegetables in 2017. Advertisements from producers of meat-based products were refused for that issue, he said.
John Brown Media, which produces the magazine for Waitrose, declined to comment on whether Sitwell continues to work within the company.