China has unveiled its most ambitious conservation plan in a generation, ahead of the opening today of a crucial UN biodiversity conference.

Foreign supporters say the move will put China at the forefront of global efforts to reverse habitat and species decline.

But critics have warned that the good intentions, as with many of the proposals that will arise at the UN meeting in Nagoya, Japan, are likely to be outweighed by economic interests. They also allege the plans are so domestically focused they will do little to halt the over-consumption and illegal trade of scarce species.

China's biodiversity action plan designates 35 priority conservation areas, covering 23% of the country; it promises state funds for protection; and sets a target of controlling biodiversity loss by 2020.

Sichuan, has been the first province to put the plan into action. It has set aside about 930m yuan (£87m) and identified five ecological protection areas: one links to existing giant panda reserves, another restores an area damaged by industry, two conserve semi-tropical flora and fauna, and another offsets the impact of dams. The national plan, which builds on China's existing 2,500 nature reserves, has been praised by foreign conservationists.

"These are solid commitments. If China can implement this plan systematically, then they will be managing better than any other country," said Matthew Durnin, lead scientist in north Asia for the US group Nature Conservancy, which has advised the drafters of the new strategy.

Ouyang Zhiyun, vice president of the Ecological Society of China, said moves were also afoot to revise wildlife protection laws and ramp up "ecological transfer funds" that reward counties for safeguarding areas that sequester carbon, conserve soil and biodiversity. This year the government has budgeted 30bn yuan for such environmental service payments, up from 12bn yuan last year.

Gretchen Daily, associate professor at Stanford University, claimed China went further than any other country in embedding "natural capital" into decision making.

But some conservationists have warned that poor enforcement often undermines such initiatives. "Sometimes the laws are not well implemented so the destruction … goes unpunished," said Yan Xie, of the Wildlife Conservation Society. "China has done a great deal, but we cannot be optimistic about biodiversity conservation while the underlying problems remain of habitat loss, pollution, overuse of pesticides and over consumption."

The 10th conference of the Convention on Biological Diversity, lasting two weeks, will try to set targets for biodiversity protection and establish rules on sustainable and fairly shared genetic resources. But, noting the failure to meet the goals it set 10 years ago, some critics doubt the effectiveness of its voluntary actions, particularly given weak international controls on the wildlife trade and the exploitation of oceans that do not fall within national boundaries.

Without cross-border arrangements, protection in one country pushes the environmental stress elsewhere, usually on to poorer nations.

Following a widespread ban on logging in 1998, China's forests have started to recover but its paper mills, flooring firms and furniture makers consume more imported wood than ever, accelerating forest loss in Siberia, Indonesia, Tanzania and Brazil. Wealthy consumers, meanwhile, continue to buy foods and traditional medicines made illegally from rare species, such as the pangolin and tiger.

• This article was amended on 19 October 2010. We said China's biodiversity action plan designates 52 priority conservation areas. This has been corrected.