World population expected to reach 10.1 billion in 2100

World population levels are projected to reach 10.1 billion at the end of the century, according to a new UN report released on Tuesday.

According to the report, titled "2010 Revision of World Population Prospects," the bulk of the expected increase in global population is projected to come from 58 "high-fertility countries" in Africa, Asia, Oceania, and Latin America. The report was prepared by the UN Department of Economic and Social Affairs (DESA) .

Fertility is "the main driver of population rates in the world, " Hania Zlotnik, director of the DESA's Population Division, told reporters here.

"The world hasn't collapsed by adding so many people, but what is important is that most of these people are being added in the poorest countries of the world," said Zlotnik.

Based on the medium projection, the number of people in the world -- currently close to 7 billion -- should pass 8 billion in 2023, 9 billion by 2041 and then 10 billion at some point after 2081, the report said.

Between 2011 and 2100, the population of high-fertility countries is expected to more than triple in size, going from 1.2 billion to 4.2 billion, the report noted. During the same period, the report projected, the population of low-fertility countries will decline by around 20 percent -- from 2.9 billion to 2.4 billion.