Eight years ago, it was estimated that only 10 per cent of the original gorilla ranges would remain by 2030 and as if that was not alarming enough, a recent UN report has warned that even these estimates were too optimistic given the present conditions.

Factors including illegal logging, mining, charcoal production and increased demand for bush meat, of which an increasing proportion is ape meat, could actually lead to complete disappearance of gorillas from large parts of central Africa by mid-2020s.

Besides, epidemics like Ebola hemorrhagic fever virus have killed thousands of great apes, including gorillas, and up to 90 per cent of animals infected by the virus will die, the report by the United Nations Environment Programme and Interpol warned.

The report, launched at the meeting of the Convention on the International Trade in Endangered Species (CITES) currently taking place in Qatar, said the situation is especially critical in the eastern Democratic Republic of Congo (DRC) where a major part of the escalating damage is linked with militias operating in the region.

It stated that the militias are behind much of the illegal trade, which may be worth several hundred million dollars a year.

"This is a tragedy for the great apes and one also for countless other species being impacted by this intensifying and all too often illegal trade," said Achim Steiner, UNEP’s executive director.

Steiner welcomed the involvement of Interpol and called on the international community to step up support for the agency's environmental crime programme.

Christian Nellemann, from UNEP who was lead author of the 2002 report and headed the new one, said the original assessment had underestimated the scale of the bush meat trade, the rise in logging and the impact of the Ebola virus on great ape populations.

"With the current and accelerated rate of poaching for bush meat and habitat loss, the gorillas of the Greater Congo Basin may now disappear from most of their present range within 10 to 15 years," said Mr. Nellemann.