BEIJING: A mystery virus that is killing millions of pigs in southern China is responsible for soaring pork prices that have the senior leadership worried about inflation and social unrest.

The Premier, Wen Jiabao, took the unusual step of visiting supermarkets and pig farms in Shaanxi province at the weekend to show the central Government's concern about the price of one of China's staple foods and its most affordable source of protein.

At the weekend, shoppers lined up for more than a kilometre at a Guangzhou supermarket to buy pork on special for 15.8 yuan ($2.50) a kilogram.