However, the number of breeding sows nationwide is up on last year, which could help stave off inflation, he told Reuters.

Rescue work is still going on for thousands buried in rubble after the May 12 quake, but with bodies in mass graves and water supplies disrupted, efforts now also include disinfection campaigns to prevent disease spreading among animals and people.

Poultry made up most of the 12.5 million birds and livestock killed by Monday's quake.

The quake has damaged infrastructure just ahead of the hot, humid summer, the peak season for diseases such as swine flu or blue ear pig disease, which decimated the hog population in 2007.

"Preventing disease is one of our largest responsibilities," Li said at a news conference in Beijing.

Li told Reuters the breeding sow population was now about 20 percent more nationwide than it was this time last year, when disease and poor profits discouraged breeding, helping to feed inflation which is now running at a nearly 12-year high.

The quake badly damaged fish farms and about 15 percent of vegetable production in the afflicted areas near the epicentre, the officials said. As many as 50,000 greenhouses were damaged.

Sichuan accounts for nearly 15 percent of China's rapeseed production, nearly 7 percent of summer grains and 5 percent of vegetables.

Although a national surplus of fertiliser should be able to make up for fertiliser plants damaged in industrial towns such as Shifang, damage to irrigation infrastructure would be harder to overcome, the officials said. Sichuan is releasing water from reservoirs to reduce pressure on weakened dams.

"Some rice paddies may have to be turned into dry fields this summer," said Wei Chaoan, vice minister of agriculture.

"Maybe, as this develops, many other problems will appear, including some we don't know about yet."