Elon Musk’s X has disabled a feature that let users report misinformation about elections, said researchers.
The tool, available in the US, Australia and South Korea since 2021, was expanded to other countries last year.
But Reset.Tech Australia said it was removed in recent weeks, except in the European Union.
In a letter, it called the move “extremely concerning”, as Australia is set to hold a referendum next month.
“There now appears to be no channel to report electoral misinformation when discovered on your platform,” said the group.
Australia’s first referendum in almost a quarter century will take place on 14 October. It will decide whether to change the constitution to establish an Indigenous advisory body to parliament.
The Australian Electoral Commission (AEC), which will oversee the referendum, has said the spread of electoral misinformation is the worst it has seen.
The move could also affect voters’ ability to report misinformation ahead of the 2024 US presidential elections.
Users can still report posts that they consider to be hateful, abusive or spam.
According to Reset.Tech Australia, the feature remains available in the EU, where a recent study suggests that X has the biggest proportion of disinformation of the six big social networks.
The European Commission study examined over 6,000 unique social media posts across Facebook, Instagram, LinkedIn, TikTok, X, and YouTube.
The platform with the largest “ratio of discoverability” of disinformation – meaning the proportion of sensitive content made up of disinformation – was X. YouTube had the lowest, the study suggested.
“My message for [X] is: you have to comply with the hard law. We’ll be watching what you’re doing,” the EU’s Values and Transparency Commissioner Vera Jourova warned in the wake of the study.
In the EU, tech giants must comply with the EU Digital Services Act (DSA), which is designed to protect users and stop election interference.
Since Mr Musk took over X or Twitter, as it was then known, in late 2022, the company has been accused of allowing a rise in hate speech and misinformation. Mr Musk denied this in a BBC interview.
He has argued that the platform’s “Community Notes” feature, which allows users to comment on posts to flag false or misleading content, is a better way of fact checking.
The BBC has approached X for comment.