The world population will reach the 7-billion mark later this year, the United Nations said Monday on World Population Day, an annual event designed to draw awareness to the challenges facing a growing populace.

The world population will reach the 7-billion mark later this year, the United Nations said Monday on World Population Day, an annual event designed to draw awareness to the challenges facing a growing populace.

"We have enough food for everyone, yet nearly a billion people go hungry," said UN Secretary General Ban Ki-moon.

He said diseases continue to spread despite medical and scientific advances, and conflict and costly armaments continue to inflict misery while "all of people of conscience dream of peace."

"We have seen many examples this year of the immense power of people to embrace hope over despair, to seek fair treatment where they are suffering discrimination, and to demand justice over tyranny," Ban said, referring to the Arab Spring.

The Worldwatch Institute, a Washington-based research organisation, said agriculture has re-emerged as a solution to mitigate a host of the world's crises, including climate change, reduce public health problems and creating jobs in a stagnant world economy.

The institute said a study on ways to nourish the planet highlights small-scale agricultural efforts to help improve peoples' livelihoods by providing them with food and income.