It also revealed that, other than the USA, covert tactics were used in at least 17 other countries to damage citizens "ability to choose their leaders based on factual news and authentic debate".
Governments around the world have drastically increased their attempts to manipulate information being shared on social media networks, contributing to a seventh consecutive year of decline in internet freedom, a global report said.
The 48-page "Freedom on the Net 2017" report by Freedom House, an organization dedicated to research of democracy and political freedom, says that elections in at least 18 countries in 2017 included significant roles played by online disinformation tactics. Most countries saw a decline in their internet freedom score, including the U.S. and United Kingdom, which now sit in sixth and ninth place.
Such tactics are also being used more generally by governments to inflate their own popularity, with paid commentators, trolls, bots, fake news sites and propaganda outlets all common tactics, according to the report.
"The use of paid commentators and political bots to spread government propaganda was pioneered by China and Russian Federation but has now gone global", said Freedom House president Michael Abramowitz, adding that the rapid spread of such techniques is "potentially devastating" for democracy.
For the third consecutive year, China was the worst abuser of internet freedom in the world, followed by Syria and Ethiopia.
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Governments in 30 of these countries are using manipulation tools to distort online information, compared to 23 per cent past year.
The Philippines is a prolific example of a country deploying such technologies.
The report said less than one-quarter of Internet users in the 65 countries assessed have access to the web that can be considered "free", meaning there are no major obstacles to access, onerous restrictions on content, or serious violations of user rights through unchecked surveillance or unjust repercussions for legitimate speech.
It said the countries with the fewest government Internet restrictions were, in order, Estonia, Iceland, Canada, Germany, Australia and the United States.
The report follows attempts by Russia to meddle with the USA presidential election between June 2015 and May 2017, when adverts paid for by a Russian organization called the "Internet Research Agency" appeared on American citizens' Facebook pages in an apparent bid to fuel political discord.