China should redouble its efforts to protect enough arable land to produce grain for its growing population and meet the expanding demands of its middle class, a senior UN official has said.

Kanayo F. Nwanze, president of the International Fund for Agricultural Development, said Chinese leaders have been faced with a two-fold challenge in feeding the country's population, even though Beijing has attached great importance to high-tech input into agriculture for years.

"For China, limited access to agricultural land but a growing population has always been a challenge," Nwanze told China Daily as China's leaders convened in Beijing to determine the development blueprint for the next five years.

Meanwhile, a ceremony was held on Friday in the organization's headquarters in Rome to unite the world's efforts in fighting hunger, which affects almost one billion people.

Nwanze said China has a population of more than 1.3 billion, which is 17 percent of the world's total, but it has less than 9 percent of the world's agricultural land.

"So, the biggest challenge is to have access to agricultural land to feed its growing population," he said.

China has already decided to increase urbanization and, by 2020, 300 million people - equal to the population of the United States - are expected to move into cities. Meanwhile, industrial development has also used large amounts of land, despite the fact that the government has decided to protect at least 120 million hectares of arable land.

However, Nwanze said the other challenge is that, with rapid economic growth and an expanded middle class, Chinese people are likely to change their dietary preferences from mainly vegetables to more meat.

Official figures show that it takes up to eight kilograms of grain to produce one kilogram of beef and five kilograms of grain to produce one kilogram of pork.

"All these rely on more grain and, as you are going to adapt from high vegetable diets to more meat diets, your consumption of grain will increase," said Nwanze.

But he said China has intensively used high technology in agriculture, which has boosted production and yields for years.

"What the world should learn from China is that you have a solid agricultural background," said Nwanze.

On Friday, the Food and Agriculture Organization of the United Nations appointed Italian actor Raoul Bova, Canadian singer Cline Dion, Filipino singer Lea Salonga and American actress Susan Sarandon as Goodwill Ambassadors to help in the global fight against hunger.

They joined the World Food Day ceremony in Rome, which takes as its theme "United Against Hunger".

This year is a significant one in the world's fight against global hunger because it marks 30 years since the first World Food Day and 65 years since the founding of the United Nation's Food and Agriculture Organization.

But Nwanze said the fact that nearly a billion people remain hungry, even after the recent food and financial crisis have largely passed, indicates a deeper structural problem.