Global population is projected to reach seven billion on October 31 this year, according to an estimate unveiled today by the UN Population Fund and others.

The UN body will work with related organisations to hold a series of activities related to the milestone starting on World Population Day on July 11, it said.

A week-long countdown is also planned, starting on October 24, which is United Nations Day.

"A world of seven billion people is both a challenge and an opportunity," said Babatunde Osotimehin, executive director of the UN agency.