Twitter Inc said that its internal controls were allowing it to weed out accounts being used for "promotion of terrorism" earlier rather than responding to government requests to close them down.
U.S. and European governments have been pressuring social media companies including Twitter, Facebook Inc and Alphabet Inc's Google to fight harder against online radicalization, particularly by violent Islamist groups.
Twitter said it had removed 299,649 accounts in the first half of this year for the "promotion of terrorism", a 20 percent decline from the previous six months. Three-quarters of those accounts were suspended before posting their first tweet.
Less than 1 percent of account suspensions were due to government requests, the company said, while 95 percent were thanks to Twitter's internal efforts to combat extremist content with "proprietary tools", up from 74 percent in the last transparency report.
Twitter defines "promotion of terrorism" as actively inciting or promoting violence "associated with internationally recognized terrorist organizations."
The vast majority of notices from governments concerned "abusive behavior", which includes violent threats, harassment, hateful conduct and impersonation.
(Reporting by Julia Fioretti; Editing by Keith Weir)