A protester wearing an Anonymous Guy Fawkes mask takes part in a demonstration in front of the Concorde square in Paris, as part of a 'popular march' gathering Anonymous and Indignant protesters, to denounce an 'electoral farce', on April 21, 2012, on the eve of the first-round poll of French presidential election / KENZO TRIBOUILLARD/AFP/Getty Images

Many of the accounts are being restored following complaints to the site, likely meaning that they are being shut down in response to complaints

Twitter is closing accounts run by people affiliated with Anonymous because they are harassing Isis, online activists have claimed.

Users that are posting messages as part of the Anonymous “war on Isis” are losing access to their accounts, according to the people affiliated with the group.

Anonymous supporters use Twitter to find out accounts supporting Isis, report them and have them shut down. Twitter claims to have shut down 125,000 Isis-related accounts since mid-2015, and supporters of Anonymous have claimed credit for helping discover those users.

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But now those supporting Anonymous claim to have had their accounts removed. Some of the largest and most-followed accounts related to “OpISIS” report having their accounts shut down.

It isn’t clear why the accounts are being taken down. But they are often reinstated soon after, according to the account holders, likely meaning that the blocks or automated or happening in response to user complaints.

Twitter has promised to strengthen its approach to online harassment of all forms, and has taken to removing more accounts for a range of different violations.