SAO PAULO, Oct 28 (Reuters) - Human rights groups and researchers have raised concerns in Brazil that social media platforms are failing to effectively police disinformation ahead of a highly polarized presidential vote on Sunday. Brazil's Superior Electoral Court (TSE) bolstered measures this month to tackle disinformation around the election, especially on video sharing platforms. "Social media platforms are failing Brazil's voters," said Deborah Brown, a senior researcher on digital rights at Human Rights Watch, who called the platforms and messaging apps "extremely important" spaces for electoral debate. "That space has been riddled with electoral disinformation, such as baseless allegations of electoral fraud," she said. "Social media companies bear some responsibility for the country being on tenterhooks about this year's election," Friedrich said.

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