BEIJING -- China has not approved any commercial production of genetically modified (GM) staple food, Minister of Agriculture Han Changfu said Thursday.

"We have been cautious over GM food because we want to make sure that it is safe," he told a press conference on the sidelines of the annual session of the National People's Congress, the country's top legislature.

The minister also called for innovation in agricultural technology, including GM technology.

China granted biosafety certificates to two pest-resistant GM rice varieties and one variety of corn in 2009, the first country to field trial GM staple foods.

"The government has never allowed any other GM agricultural products to be planted except cotton and papaya," Han said.

Adding that the country's GM safety regime remains strict, he threatened severe punishment for any unauthorized GM crop sales, planting and field trials.

GM food remains controversial nearly two decades after being introduced to the commercial market, and there is still no consensus on whether or not they are harmful to humans.

A total of 28 countries have planted GM crops. As much as 81 percent of soybeans, 35 percent of corn and 30 percent of oilseed rape in the world are GM products, according to the International Service for the Acquisition of Agri-biotech Applications, a non-profit international organization devoted to promoting crop biotechnologies.

Debate on the safety of GM food have been renewed in China since last year when celebrities joined netizens and experts to appeal for the consumers' right to know when buying GM products.

In China, 90 percent of soybean oil, which accounts for more than half of cooking oil consumption, is made from GM soybeans.

Han said that he himself consumes food containing GM ingredients.

"Whether the GM food is safe or not should not be decided by departments or individuals, it should be decided by scientists following strict standards and procedures," he said.

China has set up committees of experts to supervise the GM crop safety management.

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