The Ministry of Agriculture has given regular updates about the outbreak of blue ear disease to the United Nations Food and Animal Organisation (FAO) and the World Organisation for Animal Health since the disease was detected, said Jia.

"This has prevented unnecessary suspicion and misunderstandings and helped the international community understand the situation," he added.

An article published in the New York Times last week said China had failed to share tissue samples of affected pigs with the international community and that its lack of transparency about the disease was generating fears of a global panic.

Jia said the ministry is prepared to provide such samples, but no international body had made any requests for them.

"We welcome any party to cooperate with China in disease prevention and control," said Jia, adding that China had already sent vaccination samples to neighboring Vietnam, where a similar epidemic was detected.

Guo Fusheng, a technical advisor with the FAO China branch, confirmed that the organisation has not yet formally asked China for tissue samples.

Acknowledging China's promise of co-operation, Guo said the FAO will conduct a field trip next week to decide which sample to collect.

By Saturday, the blue ear pig disease had spread to 26 provinces, autonomous regions and municipalities on the mainland, killing 68,000 pigs and prompting officials to destroy an additional 175,000 pigs, said Jia. Shandong, Sichuan, Heilongjiang, Jilin and the Tibet Autonomous Region remain unaffected.

The country has so far vaccinated 100 million pigs against the disease, Guo said. The disease, which does not affect people, can be fatal for pigs.

"We have seen initial signs of success in controlling the outbreak of the highly pathogenic blue ear pig disease," said Jia.

Agriculture Minister Sun Zhengcai proposed early this month that all vulnerable swine be vaccinated by the end of November.

"We could meet that goal if the vaccination makers ramp up production," said Wang Changjiang, director of the Division of Animal Disease Prevention and Control.

Eleven factories are now producing the vaccine. They will have a daily production capacity of 250 million ml in September, greatly easing the shortage, said Jia.

Though developed over the course of just half a year, which is less time than usual for a vaccine, Jia said the formula had been subjected to strict scientific procedures and was up to international norms.