He gave assurances farmers would be paid back via grain and cash subsidies, tax breaks and new income from cash crops like fruit trees.

"We expect as a result some of the farmers will even increase their income after the programme is implemented," Lei told a news conference.

He gave the most detailed account yet of of what he labelled "unprecedented" plans to stem forest shrinkage and rapid desertification in a country bracing itself for a huge environmental clean-up ahead of the 2008 Olympics.

The total investment would amount to several hundred billion yuan, he said but gave no exact figure.

Recurring sandstorms, which in spring turned Beijing's skies yellow, orange and red, have become a lightning rod for fresh concerns over China's man-made ecological imbalance.

The sandstorms could be blamed in part on shepherds' flocks overgrazing, loggers over-harvesting timber, and farmers clearing trees for cropland, as well as rampant overuse of water resources and "irrational" foraging for branches and grasses, Lei said.

China has earmarked 10 billion yuan ($1.21 billion) a year for natural forest protection efforts formally launched in 2000, one of six key forestry programmes to be underway by the end of this year, he said.

A seeding programme to convert cropland to woods would raise forest and grass cover in China by 5 percent, said Lei. The resulting green belts could reduce wind speeds by 30 to 50 percent and cut sand and dust by 99 percent over barren land.

"If we increase the forest cover, then we can relieve to a certain extent the occurence of sandstorms," he said.

PEOPLE IN THE WAY

But there is teeming scepticism over China's clean-up campaign despite a regular flow of billion-dollar promises to battle smoggy skies, polluted lakes and sludge-filled rivers.

The clean-up is particularly tricky in the countryside, where two thirds of China's 1.3 billion people suffer low incomes and high taxes, and seem to have no choice but to ravage the land.

Lei said China had not fundamentally reversed its ecological decay due to inadequate, low-quality and unevenly distributed resources - including 741,000 redundant forest workers.

He said China was under enormous pressure because of high population and fast economic growth.

Local governments would find their funding cut off if they failed to properly implement forestry projects, such as strict logging bans in 13 provinces in middle and upper reaches of the Yellow and Yangtze Rivers.

The government would relocate 180,000 people around Beijing and nearby Tianjin in an attempt to rein in sandstorms with new forests and grasslands.

Farmers in protected areas would receive subsidies for eight years if they planted trees, for five years if they cultivated cash crops and for two years if they grew grass, he said.