UNITED NATIONS, Feb 25: 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 in developing countries, the United Nations Population Division says in its revised report for 2004.

Almost all of the increase will take place in the less developed countries. Their populations is expected to reach 7.8 billion in 2050 from 5.3 billion now, while the population of the more developed countries will remain around 1.2 billion, it says.

Between 2005 and 2050, 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. It says the population would at least triple in Afghanistan, Burkina Faso, Burundi, Chad, Congo, the DRC, Timor-Leste, Guinea-Bissau, Liberia, Mali, Niger and Uganda.

In 2002, the division had estimated a population in 2050 of 8.9 billion and last week, in a report sent to the 47-member UN Commission on Population and Development, had calculated the figure at 9 billion, reaching the 7 billion mark by 2012.

"World Population Change 1950-2050, the 2004 Revision" is the first of three volumes by the division on global population trends. "The world has added nearly 500 million people since 1999-- just six years," Hania Zlotnik, the new head of the division, told a press briefing.

"The good news is that new estimates show that it will take a little longer to add the next half billion, reaching the 7 billion mark probably by 2013." A summary of the report says: "Future population growth is highly dependent on the path that future fertility takes."