Twitter users will see a drop in their follower counts this week as the company clamps down on “problematic” accounts including those that have been hijacked to spread abuse, misinformation and propaganda.

Starting on Wednesday, Twitter will remove all locked accounts from people’s follower numbers. Most people will see a change of “four followers or fewer” but accounts with larger followings will experience a “more significant drop”, the company said.

Twitter locks accounts when it detects “sudden changes in account behaviour” – for example, if the account tweets a large volume of unsolicited replies or mentions; if the account posts misleading links; or if a large number of other accounts block the account in question. Accounts can also be locked if the platform finds that someone’s login credentials have been leaked elsewhere, for example through a data breach at another service.

In both cases, Twitter contacts the owners of the account and asks them to validate the account and reset their password. If the owner doesn’t comply, the account remains locked.

“In most cases, these accounts were created by real people, but we cannot confirm that the original person who opened the account still has control and access to it,” said Vijaya Gadde, from Twitter’s trust and safety team, in a blogpost.

Twitter said these accounts were different from spam accounts, which typically exhibit spammy behaviour from the beginning and so are easier to identify.

Unilever’s chief marketing officer Keith Weed, who has been an outspoken critic of “toxic” social media content, welcomed the update.

“Our digital ecosystem is being polluted by a growing number of fake user accounts, so Twitter’s commitment to cleaning up the digital space should be welcomed wholeheartedly by everyone, from users of the platforms, to creators and advertisers,” he said.

“People having an artificially-inflated follower count made up of bots and redundant accounts is at best deceiving and at worst, fraud. It serves no one and undermines trust in the entire system.”

The crackdown is part of Twitter’s renewed effort to build trust and foster a more “healthy” conversation on the platform.

“Follower counts are a visible feature, and we want everyone to have confidence that the numbers are meaningful and accurate,” Gadde said.

In March, Twitter’s CEO, Jack Dorsey, pledged to tackle the rampant harassment, bots, misinformation and polarisation in a more strategic way.

“We aren’t proud of how people have taken advantage of our service, or our inability to address it fast enough,” Dorsey tweeted.

“We’ve focused most of our efforts on removing content against our terms, instead of building a systemic framework to help encourage more healthy debate, conversations, and critical thinking. This is the approach we need now.”

In May, the company announced a global change to its ranking algorithm to push tweets from bothersome accounts lower down the in the list of replies or search results, in an attempt to mitigate the impact of mob harassment against a particular user.