Twitter has revised its strategy for fighting abusive internet "trolls," saying it will use behavioral signals to identify harassers on the social network and then limit the visibility of their tweets.

The site, known for freewheeling discussions since it was founded in 2006, has been trying to rid itself of harassment out of concern that personal attacks were driving people away.

Twitter's rules already prohibit abuse, and it can suspend or block offenders once someone reports them. Users can also mute people they find offensive.

Chief executive Jack Dorsey said Twitter now will try to find problematic accounts by examining behaviour such as how frequently people tweet about accounts that do not follow them or whether they have confirmed their email address.

Tweets from those accounts will appear lower in certain areas of the service, such as search results or replies to tweets, even if the tweets themselves have not been found to violate any rules.