Paris City Council has rejected plans for a new skyscraper on the city's 19th-century skyline - but the mayor immediately rejected the vote as invalid.

The exceptionally bitter vote embodies a larger debate over whether Paris should be a museum city or more open to modern architecture.

The council voted 83-78 in a secret ballot against the Tour Triangle, which would be the third-highest tower in Paris after the Eiffel Tower and the Montparnasse tower, often decried as a modern blight on the city's low-slung horizon.

Socialist Mayor Anne Hidalgo is in favour. Some conservative council members disclosed how they voted, which she said violated the rules of a secret ballot.

Ms Hidalgo declared its results invalid, apparently hoping for a new vote.

She said: "The law hasn't been applied... the vote is invalid." She said she would bring the matter before an administrative court.

The Swiss architectural agency Herzog and De Meuron, which designed the skyscraper, would not comment on the vote.

The Tour Triangle revives the collective trauma over the controversial Montparnasse tower, still criticized as an architectural error by many Parisians more than 40 years after its construction.

Polls repeatedly showed their strong reluctance over skyscrapers in a city famous for its preserved architecture.

The Tour Triangle is designed to host offices on 42 floors near Paris' main exhibition centre at Porte de Versailles on the city's southern edge.