The highly infectious blue-ear pig disease has killed 68,000 pigs across China and led to another 175,000 being slaughtered, Jia Youling, chief veterinary officer at the Ministry of Agriculture, told reporters.
Some Western press reports have said the number of infected pigs is much higher than the government has made public, citing the dramatic spike in pork prices in China this year as evidence.
"Although there may be some cover-ups (by local authorities), it is absolutely impossible the figure could be as big as several thousand, millions or 10 million as reported by the media," Jia said.
"Panic was caused because people didn't know (it was) blue-ear disease and had no idea how to deal with it. But it doesn't mean the number of infected pigs is huge."
In reply to criticisms that China didn't send tissue samples to labs outside the country, Jia said no such request had been received but authorities would be happy to cooperate.
"If international organisations submit their request and it's not for commercial purposes, I think we will reach agreement as soon as possible. We will cooperate and supply (the samples)," he said.
Jia said that an effective vaccine had been developed and distributed to the regions most seriously hit, and that the spread of the disease was now under "preliminary control".
He said more than 100 million pigs had been vaccinated.
"So far, no blue-ear disease has been found in places that have done the vaccination."
Jia said China last year had 500 million pigs, the staple meat in most Chinese diets, in stock.
China was heavily criticised in 2003 for initially covering up the Severe Acute Respiratory Syndrome, which originated in the south of the country.
SARS crossed over from animals into humans, eventually killing more than 800 people worldwide.