Unionen, which represents 600,000 private sector workers, is encouraging female members to call a hotline to report instances of male colleagues patronisingly explaining things to them, or 'mansplaining'.
Among those manning the phones will be feminist politicians, comedians and scientists.
In an article introducing the campaign, Unionen writes that a study by the American Psychological Association found that men “tend to overestimate their intelligence to a much greater extent than women.”
“The study also showed that self-assurance in men grows with age,” it continued. It claimed that the hotline would help both men and women “handle this kind of behaviour in your workplace.”
But the initiative unleashed a flood of negative comments on Unionen's Facebook page, particularly from men.
“How would women react if you used words like 'old biddy chat' or 'female whining'? Equality can't be won using negative invective, but should be built using mutual respect and partnership. But maybe I'm the only one who thinks so,” Daniel Bergman of Sundsvall wrote on their Facebook page.
Others, such as Jim Brännlund from Stockholm, were even blunter:
“Just what we need in society, more polarisation. And people wonder why right-wing populism is on the rise. You. Are. Retarded,” he wrote.
Others defended the campaign, however. Linda Landgren wrote:
“Good initiative. Judging by the comments, it seems quite a lot of men feel this is aimed at them, so it shows how much this kind of work is needed.”
Some said that while they would support a campaign against sexist behaviour, they thought that the references to 'mansplaining' should be removed.
“Change the name of the event, 'Mansplaining' is incredibly sexist,” Fanny Uppenberg said.
Rebecca Weidmo Uvell, a popular centre-right blogger, slammed the campaign in a post in which she claimed that she had experienced more problems with women, “particularly those who are a bit older, but also those of the same age”.
“What links them is that they are insecure, and therefore unpleasant, territorial women who have refined their suppression techniques to perfection, and who therefore have no problem trying to embarrass or put me down, preferably in public.”
“But one of the country's largest unions with almost 300,000 female members assumes that hardly any of these share my experience.”
Unionen responded to the reactions in a Facebook post, in which it said it was pleased that the subject was arousing so much passion.
“The purpose of the campaign is not to point fingers or to blame all men. The campaign is intended to make us all, men and women, aware of this phenomenon and hopefully to start a change together. Everyone wins when we expose suppression techniques and talk about them,” Gabriel Wernstedt, spokesman for Unionen told The Local in an email.
“It's naturally unfortunate if some people are offended by our mansplaining hotline. At the same time these are questions that affect many people and that people want to discuss. We can also note that many people are positive about us raising the question of mansplaining. The attention has exceeded our expectations and shows that this is an important question,” he continued.