A gym in South Korea has banned misbehaving "aunties", reigniting a debate about discrimination against older women in the country.

The gym in Incheon city near the capital Seoul put up a sign that read "off limits to ajummas" and "only cultivated and elegant women allowed".

Ajumma is a catch-all term for older women - typically late-30s onwards - but is also a pejorative for behaviour that is seen as rude or obnoxious.

Local reports did not name the gym or its owner, who defended the move, claiming that his company had "suffered damages" because of these women and their unruly behaviour.

“[Some older women customers] would spend an hour or two in the changing room to do their laundry, steal items including towels, soaps, or hair dryers,” he said in a televised interview with South Korean news agency Yonhap.

“They would sit in a row and comment and judge other people’s bodies,” he said, adding that some younger women have quit the gym because of these comments, which upset them or made them uncomfortable.

While the move was made by a single gym, it seems to have struck a nerve because, in recent years, South Korean businesses have drawn flak for banning children or seniors from certain public places.

Some of this has been seen as proof of growing intolerance for specific age groups.

The gym has also drawn criticism for conflating bad behaviour with women of a certain age.

“How did the term 'bad customer' become the same as 'ajumma'?", read one comment on local social media website instiz.

"If you have worked in the service industry, you’d know that it’s not just older women who fall into those categories.”

Another comment described the move as a sign of outdated attitudes, calling it "sentiments of the early 2000s”.

The gym defended itself by pointing to an additional notice that tried to distinguish between ajummas and women. It says that ajummas tend to "like free stuff regardless of their age", and that they are "stingy with their own money but not with other people's money".

The gym's owner also said there may be other business owners who share his sentiments but have not spoken out.

"It’s not that I tried to make a hate comment against older women or women in general," he told Yonhap. "I think people who are enraged by [the notice] are in fact the ones with the problem."

The ban did find support among some people online, who also seemed to associate ill manners with older or middle-aged women. Some described them as "territorial", while others used insulting language, calling them "senseless".

"The ladies are annoying... They take their kids to restaurants and cafes. They are oblivious and abusive," read one comment on YouTube.

There were multiple references to children, with the main notion being that these women took up a lot of space or attention in public spaces.

South Korean women have long fought for non-traditional choices - from short hair to singledom - in a society that holds them to often unyielding standards. Women say men are rarely judged for similar behaviour.

Commentators too have pointed out that there was no need to single out women at all, when older men are just as likely to behave badly.

“Older men behave the same," psychology professor Park Sang-hee said in an interview with television network JTBC, following the ban. "Older men also obsess over free stuff and repeat themselves over and over again. Rude behaviours are not exclusive to older women."