About 3.9 billion people are now using the internet, meaning that for the first time more than half of the global population is online, the United Nations has said.

The UN agency for information and communication technologies, ITU, said that by the end of 2018 a full 51.2% of people around the world will be using the internet.

"By the end of 2018, we will surpass the 50/50 milestone for internet use," ITU chief Houlin Zhou said in a statement.

"This represents an important step towards a more inclusive global information society," he said.

Though, he added, that "far too many people around the world are still waiting to reap the benefits of the digital economy".

He called for more support to "technology and business innovation so that the digital revolution leaves no one offline".

According to ITU, the world's richest countries have been showing slow and steady growth in internet use, which has risen from 51.3% of their populations in 2005 to 80.9% now.

The gains have meanwhile been more dramatic in developing countries, where 45.3% of people are currently online, compared to just 7.7% 13 years ago.

Africa has experienced the strongest growth, with a more than ten-fold hike in the number of internet users over the same period, from 2.1% to 24.4%, the ITU report showed.

From this week, Cubans were able to access the internet on their mobile phones, state-run telecoms monopoly ETECSA said.

It marked a milestone for what has long been one of the Western Hemisphere's least connected countries.

Nearly half of the Communist-run country's 11.2 million residents have a mobile phone, although not all will be able to afford mobile internet.