Twitter is making headway in tackling online terrorism content on its platform as it suspended over 166,000 accounts in the second half of last year, about a fifth less than in the previous period, the social media company said on Thursday.

Together with Facebook and Google, Twitter is under pressure from regulators and governments worldwide to remove extremist content more rapidly or face more heavy-handed legislation.

Announcing its latest transparency report, the company said its technical tools were producing results, with 91 percent of accounts promoting terrorism content proactively suspended by its internal technology, the majority of which happened before their first tweet because the data used to set them up raised red flags.

Twitter suspended 166,153 accounts between July and December last for promoting terrorism, a 19 percent drop from the 205,156 accounts suspended in the previous six months.

"This sharp decrease is indicative of a larger trend we are now observing — year-on-year the numbers of terrorist organizations attempting to use our service is reducing," Sinead McSweeney, Twitter's vice president for public policy said in a statement.

"This can be attributed to a robust technical approach that we've enhanced over many years. We are encouraged by these metrics but will remain vigilant," she said.