The accelerated and unsustainable exploitation of the earth's primary natural resources has become a major threat to apes in Africa and Asia, a major United Nations environment conference heard Wednesday.

Speaking on the sidelines of the UN Environment Assembly, conservationists said infrastructure development and extraction of natural resources -- including timber, minerals, oil and gas -- have devastated the prime habitat of apes and pushed chimpanzees, gorillas, bonobos, orangutans and gibbons closer to extinction.

"There's absolutely no doubt that extractive industries are severely impacting on apes and their habitats," said Helga Rainer, conservation director of the Great Apes programme at the Arcus Foundation, the world's largest private funder of ape conservation.

"Only five out of 27 ape (habitats) do not have a mining project within their range... and there is also an indirect impact associated with infrastructure development such as roads and railways," she added.

But while the cost to apes of economic development has been acknowledged for decades, researchers say more needs to be done to integrate their preservation into broader social, economic and environmental policies.

"We need to develop safeguards and environmental policies that can address these issues effectively," said Jef Dupain, director of the African Apes Initiative at the Nairobi-based African Wildlife Foundation.

Experts predict that at the current rate, human development will have impacted 90 percent of the apes' habitat in Africa and 99 percent in Asia by 2030, according to a new report titled "State of the Apes: Extractive Industries and Ape Conservation".

All species of apes are listed as endangered by the International Union for the Conservation of Nature (IUCN), some critically so.

There are about 880 mountain gorillas across Uganda, Rwanda and Democratic Republic of Congo, while Cross River gorillas in Cameroon and Nigeria are thought not to exceed 250.

"There's a lot of pressure from mining activities, so you can see the pressure being exerted," said Andrew Seguya, executive director of the Ugandan Wildlife Authority.

In Asia, Sumatran orangutans are believed to have declined by 50 percent since 1992, and the entire population of Hainan black-crested gibbons in China amounts to just 21 individuals.

"A key message of 'State of the Apes' report is that the global systems of production, consumption and demography are interconnected, and that rapid globalisation will continue to exert intense pressure on natural resources and ape habitats," officials said in a joint statement.