BEIJING, Dec. 30 -- Although China's latest national land survey showed better-than-expected arable land figures, the country's growing population, accelerating urbanization and pollution are eroding the country's arable land and threatening food security.

According to the results of the second national land survey released on Monday, China's arable land totaled 2.03 billion mu (about 135.4 million hectares) at the end of 2012, 227 million mu more than the "bottom line" set by the government to ensure food security.

The total arable land area was larger than in the previous land survey. However, the actual available arable land was just slightly above the government's red-line after deducting land arranged for forest and pasture restoration or land deemed not suitable for farming because of pollution, said Wang Shiyuan, vice minister of land and resources at a press conference.

The three-year survey showed that China's per capita arable land area shrank to 1.52 mu by the end of 2009, far below the world average of 3.38 mu, Wang said.

Wang said China must step up efforts to guarantee the arable land red-line, as the per capita figure is still decreasing due to a growing population and accelerating urbanization process.

To make the situation worse, soil pollution is also hurting farming, with around 50 million mu -- about 2 percent of the country's arable land -- too polluted with heavy metals or other waste to be used for growing food, according to Wang.

As the world's most populous nation, China has been striving to maintain food self-sufficiency.

The country saw another bumper year for grain production in 2013 as output gained 2.1 percent year on year to hit 601.94 million tonnes, marking the 10th consecutive year for increased grain output in China, according to statistics from the National Bureau of Statistics.

China's second national land survey was conducted between 2007 and 2009. The country's first national land survey ended in 1996.