The world's population will reach 9.7 billion by 2050 as India becomes the largest country, the UN has reported.

In 35 years' time, there will be an extra 2.4 billion people in the world owing to high fertility rates in a handful of countries.

The UN predicts that the figure will rise to 11.2 billion by 2100.

Between 2015 and 2050, half of the growth will be concentrated in India, Nigeria, Pakistan, Democratic Republic of the Congo, Ethiopia, United Republic of Tanzania, United States of America, Indonesia and Uganda.

India will surpass China as the country with the greatest population around 2022, and Nigeria is predicted to have more people than the United States by 2050.

The number of people living in 28 African countries is also expected to double, and by 2100 several countries will see a fivefold increase in their population.