SAN FRANCISCO (CBS SF) – Looking to curb online abuse, Twitter is reportedly working on tool that will let users filter out tweets that could be harassing or offensive.

Bloomberg News reported that the San Francisco-based social network has been discussing how to implement the tool for about a year. The filter could allow users to screen out offenders by blocking certain keywords, such as swear words or racial slurs.

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Sources familiar with the matter said the filter could eventually be used to block content a user doesn’t care about.

Twitter has struggled to address harassment on its platform, particularly racist and sexist attacks.

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Dick Costolo, the company’s former CEO, bluntly described the situation in an internal memo to employees last year. “We suck at dealing with abuse and trolls on the platform and we’ve sucked at it for years,” he said.

Last month, Twitter permanently banned conservative writer Milo Yiannopolis over his campaign he launched to harass “Ghostbusters” actress Leslie Jones.

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It is unclear when the blocking feature would be implemented.