India to be most populous by 2030

In its revised report for 2004, the United Nations Population Division predicted that India and China will exchange places, mainly because of differences in fertility.

India, at 1.103 billion people this year would reach 1.593 billion by 2050, which China which has 1.316 billion now will reach 1.392 billion.

"We have been saying for a while that India will cross China. But the crossover has been getting earlier and earlier and we now say it will happen before 2030 (not including Hong Kong). This is five years earlier than we said two years ago," UN demographer Cheryl Sawyer said.

The report also said that the world's population will reach 6.5 billion by July and, despite lower expected fertility rates, is likely to reach 9.1 billion by 2050, with most of the increase taking place in developing countries.

Just eight countries - India, Pakistan, Nigeria, the Democratic Republic of the Congo (DRC), Bangladesh, Uganda, the United States, Ethiopia and China are likely to contribute half of the world's population increase between 2005 and 2050, while the population would at least triple in Afghanistan, Burkina Faso, Burundi, Chad, Congo, the DRC, Timor-Leste, Guinea-Bissau, Liberia, Mali, Niger and Uganda.

Fertility in the 44 developed countries remains generally low, with any increases being small, the report says.