BEIJING, April 22 (Xinhua) -- About 12.3 million hectares, or more than 10 percent of China's arable land is contaminated by pollution and the situation is getting worse, said the Ministry of Land and Resources.

Officials and experts believed the arable land pollution, together with declining farmed area, posed a severe threat to the nation's food security, said a ministry official.

The ministry announced this month that China's arable land area had shrunk to 121.8 million hectares by the end of last October, with the loss of 306,800 hectares in the first 10 months of 2006.

The land suffered from polluted water, excessive fertilizer, heavy metals and solid wastes, the ministry official said.

The ministry acknowledged that heavy metals alone had contaminated 12 million tons of grain and caused losses of 20 billion yuan each year, adding the polluted grain would ultimately be a health hazard.

Sun Wensheng, Minister of Land and Resources, called on the public to conserve land and other resources for sustainable economic growth on Sunday, the 38th World Earth Day.

The ministry said it was working with the State Administration of Environmental Protection to seek the most suitable pollution monitoring and prevention system, as well as solutions to the problem.

The government has also tightened restrictions on the acquisition of farmland for construction of housing and factories and called for a guaranteed 120 million hectares of arable land by 2010 to ensure grain supply.