Women-only swimming classes have been axed at a leisure centre following a complaint that they discriminated against men.
The sessions at the Pulse leisure centre in Dursley, Gloucestershire, have been changed to adults only.
Stroud District Council said they hoped people would "understand we have to abide by the law".
The decision has been derided on social media and described as being against the spirit of equalities legislation.
The women-only classes have run at the centre for years and take place for an hour once a week.
But from next month the classes will be open to both men and women, after a single complaint.
"We've run these ladies-only sessions for years but we were recently contacted to justify why we ran them, as single-sex classes are likely to be in breach of the Equalities Act 2010," a spokesman for the council said.
"Consequently we've had to change the sessions to 'adults-only swims'.
"While this may not be ideal for everyone, we hope they will understand we have to abide by the law."
'Astonished and outraged'
Conservative councillor in the town Loraine Patrick said the decision went against the spirit of equalities legislation.
"To say that I'm astonished, furious, outraged is putting it mildly," she said.
"The Equalities Act is meant to give everyone a chance. But taking that session away removes that chance to swim for a lot of people, so it is not equal.
"This may be the letter of the law but is certainly not the spirit."
The decision has been derided on social media in the town, with some suggesting they will complain about age discrimination in retaliation.
Hannah Norman wrote: "I can't believe they have stopped a session that enables women the opportunity to feel safe and confident. How ridiculous. They should have just made a men-only session too."