The council issued a statement confirming the situation as a result of a complaint lodged by the campaign group 'Mugrons Lliures' of Catalonia.
Protesters claimed one woman was told to cover up and wear both parts of her bikini but said this was against the law. City leaders have now agreed.
The authority has ruled that the pools of Barcelona must not discriminate if a woman wants to swim topless because men do the same and they cannot differentiate between bikini bottoms and swimming trunks.
The council has sent a reminder to all sports centres from the Office for Non-Discrimination (OND) reminding them that 'topless' must be allowed in all its spaces, because not doing so would represent a 'discriminatory' practice when setting dress standards based on gender.
Deputy Mayor Janet Sanz stressed that this practice has never been prohibited in municipal swimming pools and what the OND has done has been to remind the centres.
The goal is that 'all women who want to do 'topless' can do it' normally in municipal centres, whether public or private.
'The Mugrons Lliures entity presented a complaint to the OND, which argued that the regulations that regulate clothing based on gender are discriminatory, so it recommends that municipal centres with swimming pools withdraw any regulations that prohibit the 'topless' in their spaces,' she said .
Mugrons Lliures said some centres had put restrictions on bathing or in specific areas of the installation by internal regulations.
Any centre which does not comply could now face a fine.
The recommendation, based on a legal report, makes no distinction about indoor or outdoor swimming pools.
Mugrons Lliures, which had complained to the Ombudsman last year about the discrimination, said it was delighted at Barcelona's announcement and expects the norm to now apply across the country.
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