Hongkongers are also feeling the pinch, as pork prices hit record highs, with a catty now costing about HK$42.

The whole world has been affected by rising food prices. The Japanese are complaining that instant noodles are becoming more and more expensive.

In September, there was a 'spaghetti protest' against the rising prices of pasta in Italy. The protesters declared a boycott of their staple food and restaurants removed pasta from their menu to force the government to tackle inflation.

There were food protests in Mexico in February. More than 75,000 people took to the streets, slamming the government for failing to bring down the price of tortilla - an everyday bread popular among the poor.

A few months ago, three people were killed in a stampede at a supermarket in Chongqing . They were among a crowd who was fighting to buy discounted cooking oil from the store.

These incidents may just be the beginning of a much larger problem. The world eats more than it produces and food prices will continue to rise, possibly leading to more social instability and malnutrition in developing countries, according to the International Food Policy Research Institute (IFPRI).

At an international food conference in Beijing last week, the IFPRI warned of a global food crisis as grain stocks, such as cereal, rice and wheat, are at their lowest levels since the 1980s. The expansion of biofuels, combined with the growing appetite of developing countries and climate change, has transformed the global food market, the IFPRI explained.

With oil prices soaring and natural energy resources, including coal, gas and petroleum, being used up rapidly, bio-energy is an emerging industry around the world. Regarded as more eco-friendly and a renewable substitute to conventional fuel, biofuels are gaining momentum in Europe and North America. They are available in many petrol stations in western countries.

Many farmlands have switched to growing biofuel raw materials, such as oilseed and maize, to earn more money.

Based on current bio-energy investment plans worldwide, the IFPRI estimates that the price of maize would rise 26 per cent by 2020. The jump would be 72 per cent if the biofuel expansion doubles.

Climate change is making the situation worse. Experts predict more extreme weather conditions, such as prolonged droughts, massive floods and powerful hurricanes, in future. Global warming could slash the world's agricultural output by 16 per cent, they warn.

A vivid example is the continuing drought in Australia which began in 2003. It has halved the country's winter wheat crop to 12 million tonnes this year.

This is a big blow as Australia is the world's second largest wheat exporter. Recently, the Australian Bureau of Agricultural and Resource Economics said they were running out of grain stocks.

Meanwhile, the wealthy population is expanding in booming economies like China and India. The newly rich are moving away from their grain-based diet and opting for more meat and dairy products.

Besides pork, vegetable and fruit prices have surged, with some poor families eating less to reduce their expenses.

Some major grain-producing countries, such as India and Vietnam, have already cut their exports.

The situation may worsen over the next two years, as countries like China start to import more food, further pushing up the prices.

To avert a food crisis, the IFPRI suggests that countries should review their bio-energy development and invest on research to increase crop yields.

Without foreign aid, poor people in developing countries would be deprived of a balanced diet, the institute said.