About a million pigs died in China last year of "high fever disease", later identified as blue ear disease, the country's top veterinary official said on Monday in the first official confirmation of the death toll last year from a disease that has pushed up China's pork prices.

China in January identified a contagious pig disease outbreak as blue ear disease, or Porcine Reproductive and Respiratory Syndrome (PRRS). The outbreak began last May.

"The 'high-fever disease' was caused mainly by the blue-ear disease virus, but other viruses cannot be ruled out," Jia Youling, head of the veterinary department of the ministry of agriculture, told reporters.

"The death rate from the 'high-fever disease' accounted for 0.2 percent of the pig population (of 500 million)," Jia said.

Last week, the Ministry of Agriculture said the disease had killed 18,597 pigs in the first five months of 2007 with outbreaks found in 22 provinces, or about two-thirds of the country's provinces and regions.

"The virus had developed into a variant that was more virulent and led to higher mortality rates," Jia told a news conference.

Last week's release was Beijing's first report on the scale of an outbreak that has disrupted the pig industry and contributed to soaring pork prices, which are threatening to push inflation above government targets.

Premier Wen Jiabao visited a pig farm last month, where he pledged to ensure meat supplies for the poor.

The disease has caused panic among pig breeding farms, Jia said.

China's central government will pay 285 million yuan ($37.13 million) for free vaccines for smaller breeding farms, where the disease was widespread last year, he said.

Low pork prices last year and high feed prices had made farmers unwilling to raise sows, which contributed more to the rising prices than did the disease, he said.

Jia did not estimate when breeding levels would recover.

($1=7.676 Yuan)