The governments of a total of 30 countries "deployed some form of manipulation to distort online information, up from 23 the previous year".
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.
These efforts included paid commentators, trolls, "bots" - the name given to automated accounts - false news sites and propaganda outlets, according to the 2017 "Freedom on the Net" report by human rights group Freedom House.
"The use of paid commentators and political bots for the dissemination of government propaganda was initiated by China and Russian Federation but is now global", said Michael Abramovitch, president of Freedom House.
"The effects of these rapidly spreading techniques on democracy and civic activism are potentially devastating", he added.
Sanja Kelly, director of the Freedom on the Net project, explained such manipulation is often hard to detect, and "more difficult to combat than other types of censorship, such as website blocking".
The organization said 2017 marked a seventh consecutive year of overall decline in internet freedom, as a result of these and other efforts to filter and censor information online.
In its annual report released late Monday, the Washington-based Freedom House said that manipulation and disinformation tactics on the internet played an important role in the elections of at least 18 countries, including the U.S., thereby "damaging citizens' ability to choose their leaders based on factual news and authentic debate", reports Efe news.
"Not only is this manipulation hard to detect, it is more hard to combat than other types of censorship, such as website blocking, because it's dispersed and because of the sheer number of people and bots deployed to do it".
This included a "keyboard army" of people employed and paid $10 a day by the Philippine government to amplify the impression of widespread support of a brutal drugs crackdown, and Turkey's use of an estimated 6,000 people to counter government opponents on social media. An example is a case in Ukraine where Russian-based services have been blocked, including the most widely used social networking and search engine in the country, in an attempt by Kiev to cope with Pro-Russian propaganda.
Freedom House said that Internet freedom improved in Iran and Uzbekistan, but those countries still had the fourth- and sixth-worst scores respectively.
It said internet freedom also took a hit in United States over the past year.
Fake news and the "aggressive trolling" of journalists both during and after the presidential election contributed to a score decline in the United States' otherwise generally free environment, the report said.