The Islamic State's English-language reach on Twitter has stalled in recent months amid a stepped-up crackdown against the extremist group's army of digital proselytisers, a study says.
Suspensions of English-speaking users affiliated with Islamic State from June to October 2015 have limited the group's growth and in some cases devastated the viral reach of specific users, according to the report from George Washington University's Program on Extremism.
The report found easily discoverable English accounts sympathetic to Islamic State was usually less than 1000, and those users' activity was mostly insular, limited to interacting with each other.
Islamic State has seized control large areas of Iraq and Syria and claimed credit for attacks in Paris in November that killed 130. The US and other governments consider it a terrorist organisation.
Twitter has long been criticised by government officials for its relatively lax approach to policing content, even as other Silicon Valley companies such as Facebook have policed their platforms more actively.
Under intensified pressure from the White House, presidential candidates and some civil society groups, Twitter announced in February it had shut down more than 125,000 terrorism-related accounts since the middle of 2015, most of them linked to the Islamic State group.
In a blog post, the company said while it only takes down accounts reported by other users it had increased the size of teams monitoring and responding to reports and has decreased its response time "significantly".
Report co-author JM Berger said Twitter was still less active than many of its rivals but part of that was due to its relative youth as a company.
"Each company has been dragged into this kicking and screaming," he said in an interview.
Reporting of Twitter accounts affiliated with Islamic State was a steady, low-level activity generally but occasionally events led to "periodic purges", Berger said.
The study took place before the Paris attacks, which the researchers said likely led to a heavy wave of suspensions mostly in French and Arabic networks.
The average tweets a day measured across the lifetime of an account also declined during the monitored interval, from a peak of about 14.5 in June to a low of 5.5 by October.
The average number of followers was measured between 300 and 400.