Only nine of the 193 United Nations countries' accounts are managed by government officials, the study by Burson-Marsteller found. The rest were privately registered early on in Twitter's history, long before the microblogging service became popular for political use and before governments began using tweets as a tool for quickly broadcasting news to a worldwide audience.

“Looking at the findings, it becomes clear that few governments and tourism organisations have understood the power of country branding and marketing on Twitter,” Matthias Lüfkens, head of the Burson-Marsteller Europe, Middle-East and Africa Digital Practice, said in a press release. “There is a huge opportunity for countries to use Twitter as part of their communications to engage with a large and growing audience.”

The nine countries that officially control their own names on Twitter are @AntiguaBarbuda, @Barbados, @GreatBritain, @Israel, @Lithuania, @Maldives, @SouthAfrica, @Spain and @Sweden. 

According to analysis of those nine accounts, Israel is the most popular country on Twitter, with more than 67,000 followers. The @Israel account is managed by the Foreign Ministry's Digital Diplomacy Team. 

Sweden's account is the second most popular, and prompted the rotation-curation movement of putting the official handle under the control of a random citizen for a week at a time that has been copied by @Ireland and @NewZealand. That experiment has proven popular, although it invited controversy in the past.

All English-language country names are registered on Twitter, although only a third of them (71 accounts) are actively used. Most are dormant (43 accounts), inactive (30 accounts), protected (13 accounts) or suspended (36 accounts), the study found.

Both @UnitedStates and @USA are registered to private individuals, although the administration does run the account @USAgov.

The study builds upon a previous "Twiplomacy" survey that found almost two-thirds of world leaders use Twitter. President Obama was the first head of state to start tweeting and is still the most popular, the July study found.