The London Guardian reported that Twitter has deleted 20,000 fake accounts linked to the governments of several countries including Serbia for what a statement said were a “targeted attempt to undermine the public conversation”.

The newspaper quoted Twitter’s head of site integrity Yoel Roth who said that the accounts had bee removed as part of efforts to “detect and investigate state-backed information operations”.

It said that 8,558 of the accounts removed on Thursday were linked to the President Aleksandar Vucic’s ruling Serbian Progressive party (SNS) and added that they had been used to post more than 43 million tweets to amplify positive news coverage of Vucic and his government and attacking his political opponents. In comparison, Twitter removed 5,350 accounts which tweeted 36.5 millon times to praise the Saudi leadership and criticize its opponents.

The accounts were removed after a warning from the Stanford Internet Observatory. Twitter has purged networks of state-backed fake accounts since coming under criticism for being used as a vehicle for disinformation. “Transparency is fundamental to the work we do at Twitter,” a company statement said. “These behaviors are in violation of our policies and are a targeted attempt to undermine the public conversation.”