Unesco is pointing to a "mobile reading revolution" in developing countries after a year-long study found that adults and children are increasingly reading multiple books and stories on their phones.

Nearly 5,000 people in seven countries – Ethiopia, Ghana, India, Kenya, Nigeria, Pakistan and Zimbabwe – took part in the research, the largest study of its kind to date, which found that 62% of respondents are reading more, now they can read on their mobile phones. One in three said they read to children from their mobile phones, and 90% of respondents said they would be spending more time reading on their mobile phones in the next year.

The study, says Unesco in its report, found that "people read more when they read on mobile devices, that they enjoy reading more, and that people commonly read books and stories to children from mobile devices".

"The study shows that mobile reading represents a promising, if still underutilised, pathway to text," says the report, for which Unesco partnered with Worldreader – a global not-for-profit organisation that works to bring digital books to readers around the world – and Nokia. "It is not hyperbole to suggest that if every person on the planet understood that his or her mobile phone could be transformed – easily and cheaply – into a library brimming with books, access to text would cease to be such a daunting hurdle to literacy."

The report's author Mark West said that the key conclusion from the study was that "mobile devices can help people develop, sustain and enhance their literacy skills".

"This is important because literacy opens the door to life-changing opportunities and benefits," said West.

Reasons given by respondents for reading on mobiles were convenience, affordability and lack of access to books. In Zimbabwe, for example, Unesco said the cost of reading a book on a mobile was between 5 and 6 cents, while a paperback bestseller would cost around $12 (£7); in Nigeria, a mobile book would cost around 1 or 2 cents, based on a mobile broadband rate of $13 per 500 MB of data, while a child's book would cost between $1 and $5.

Unesco pointed to data from the UN, which shows that of the seven billion people on earth, more than six billion now have access to a working mobile phone. "Collectively, mobile devices are the most ubiquitous information and communication technology in history," says Unesco. "More to the point, they are plentiful in places where books are scarce."

The most popular genre for readers was romance, the survey found, with the "romance" icon on Worldreader Mobile receiving 17% of all 730,787 clicks during the research period. Nineteen of the top 40 books read during the study period were romance novels, with Ravinder Singh's Can Love Happen Twice? the most popular book, followed by the Mills & Boon title The Price of Royal Duty in second, and the Bible in third.

Kwame Nkrumah's The Great African and Nnedi Okorafor's The Girl with the Magic Hands were also among the most read books between April and June 2013, with the most popular search terms over the period "sex", "Bible" and "biology". Chinua Achebe came in fourth, with "Things fall apart", ahead of "love" in fifth. Religion was the second most popular genre, said Unesco.

The survey also found that mobile reading is a "huge tool of empowerment for women", said Worldreader's Nadja Borovac. While 77% of mobile readers in developing countries are male, women spend an average of 207 minutes per month reading on their mobile phones, compared to men's 33 minutes. Unesco's report points out that in sub-Saharan Africa, a woman is 23% less likely to own a mobile phone than a man, with the gap widening in the case of data-enabled phones. "Men use mobiles for reading most, but the most active readers are women," said Borovac.

Almost two-thirds (60%) of respondents cited lack of content as the primary barrier to mobile reading, and a third said they were keen to read to their children from their mobiles if there were more child-friendly material available.

One respondent, Charles, a teacher in Zimbabwe, said he reads to his class from his mobile, and cited lack of printed content as his main reason for turning to his phone. "We live in a remote area where there are no libraries, and the books I have in my own small library are the ones which I have already read. So this is now giving me a chance to choose from a variety of fiction titles," he said.

Borovac said that mobile reading was "not a future phenomenon, but something which is happening today".

"It can really change people's lives," she said. "We work in countries where there is a serious shortage of books but where cell phones are plentiful ... We are hoping people will realise the potential of mobile reading [as a result of the report], and that governments and partners will get behind not only us but other organisations using mobile technology to help provide learning and books, and help improve literacy skills."