China has ratcheted up its campaign to cool the booming property market by stopping land sales for villas and other luxury housing projects.

The government said the move was also designed to help protect the nation's dwindling reserves of farmland.

Authorities across the nation will now have to screen projects for violations of the new land-use regulations, Wang Shiyuan, vice minister of land and resources, told a news conference in Beijing on May 31.

Local land resource bodies must give priority to developers of moderately sized and priced apartments - those that average wage earners can afford, Wang said. Local governments must also publish land sales records to ensure transparency, he said.

And China's Central Bank will tighten scrutiny on lending to limit "excessive investment and loans growth," the state news agency Xinhua said. From this week, measures come into force forcing homebuyers to increase down-payments from 20% to 30% and forcing a 5.5% tax on homes sold within five years.

A day before the news conference, China issued an emergency order urging local authorities to exercise more caution in considering applications for developing land for non-agricultural projects.

China lost more than 122 million hectares of farmland last year to construction projects and natural forces such as erosion.

"The country cannot afford the construction of large villas to meet the demand of a few high-end customers while sacrificing the interests of the majority," said the vice-director of China's Land Ministry, Shu Kexin.