If the government does not protect wildlife from commercial exploitation, illegal logging and poachers, orangutans there could be extinct by 2011, said Hardi Baktiantoro, the group's head.
He said more than 5,000 orangutans in the region have been lost every year since 2004, due largely to loss of habitat.
Adding to the problem is a plan by Indonesian authorities to open up 1.1 million acres -- an area larger than the state of Rhode Island -- of protected land for palm oil growers, he said.
Indonesian President Susilo Bambang Yudhoyono announced a major initiative to save the nation's orangutans at the Bali Climate Conference last year, but it appears the plan has not received sufficient political support.
Toni Suhartono, the Forestry Ministry's top official for wildlife protection, said government programs to save the environment are hampered by a lack of funds and lack of knowledge about conservation.
Awareness "about the conservation of endangered species is very low. It is, therefore, not easy for us to propose budgets for conservation," Suhartono said.