US President Donald Trump is by far the most followed world leader on Twitter, with Pope Francis trailing him by 4.5 million followers, a study has found.

The number of Mr Trump's followers has "more than doubled since taking office", the study authors said.

With more than 52 million followers, the @realDonaldTrump account also counts nearly ten million more followers than third-place holder, Indian Prime Minister Narendra Modi, according to the latest "Twiplomacy" study by communications firm Burson Cohn & Wolfe.

In terms of interactions with followers, in the form of likes and retweets, Mr Trump's lead is even more impressive, the study showed.

Over the past 12 months, the US president has had nearly 264.5 million interactions with his followers, more than five times more than runner-up Mr Modi, and 12 times as many as Pope Francis, in third place.

However, in terms of retweets alone, Saudi Arabia's King Salman easily dwarfs Mr Trump.

Mr Salman only tweeted 11 times between May 2017 and May 2018, but each of those tweets generated an average of 154,294 retweets, compared to just 20,319 retweets per Trump tweet, the study found.

It also pointed out that the US State Department is the only US governmental department which does not follow the personal account of @realDonaldTrump.

The State Department does follow Iranian Foreign Minister Javad Zarif and Iranian President Hassan Rouhani.

Leaders around the world have jumped on the Twitter train, with the governments of only six countries, Laos, Mauritania, Nicaragua, North Korea, Swaziland and Turkmenistan, still lacking an official presence on the platform.

In Europe, British Prime Minister Theresa May was the most followed leader on Twitter over the past year, with the @10DowningStreet account counting nearly 5.6 million followers.

The British royal family came next with 3.6 million, followed by French President Emmanuel Macron, who has nearly tripled his numbers since his election last year to over three million Twitter followers.

Queen Rania of Jordan ranks at the top of the twittersphere among Arab leaders with nearly 10.7 million followers, ahead of Dubai ruler Sheikh Mohammed with over nine million followers, and King Salman on nearly seven million.

Latin American governments are among the most prolific on twitter. 

Venezuela's foreign ministry sent out an average of 55 tweets each day over the past 12 months, according to the study.

While most world leaders and governments are growing their Twitter followings, there are exceptions.

According to the study, Russian Premier Dmitry Medvedev, the Russian foreign ministry, and the Ukrainian foreign ministry have seen their number of followers decline significantly "after Twitter decided to cut down on fake followers and bot farms".

BCW's own review of 951 Twitter accounts showed that 125 of them, 13%, were currently dormant, 33 inactive and nine protected.