Nepal's government officials said Sunday that the massive bird flu outbreaks, which are not yet controlled even after chicken trade ban, were due mainly to the vaccines administered haphazardly to chickens by the poultry farmers.

"The poultry farmers imported and used the vaccines haphazardly without first consulting the government's veterinary doctors and experts," Narayan Ghimire, spokesperson of the government's bird flu control campaign told Xinhua.

As the vaccines were unverified, the virus grew so rapidly and strongly that it became difficult to control, said Ghimire.

As the experts say, before injecting a particular vaccine that contains small amount of bird flu virus, first the species of bird flu present in a fowl has to be determined.

If one type of vaccine is administered in a fowl infected with another type of bird flu, the vaccine suppresses symptoms of the disease for a short period. However, in the long run, the virus in this case spreads both in quantity and quality.

To deal with this problem, the Ministry of Agriculture, a few weeks ago, formed a committee chaired by Ram Krishna Khatiwada, the deputy director general at the Department of Livestock Services.

According to Khatiwada, a team of experts from the Food and Agriculture Organization and World Health Organization is visiting Nepal shortly to study the problem and suggest measures.

"We will be able to recommend the appropriate vaccines, only after the team submits its final report," said Khatiwada.

Since the beginning of new fiscal year on July 16, at least 40 bird flu cases have been reported alone in Kathmandu valley.

Following a large number of outbreaks in a short span, the government authorities imposed a one-week ban on sales and supplies of chicken products from Aug. 1 to 7.

The ban has been lifted, but cases of bird flu are still emerging out in various poultry farms of the Nepali capital.

In particular, among three districts of the capital valley, Bhaktapur has been affected the most, followed by Kathmandu and Lalitpur. More than 30 cases have been reported alone in Bhaktapur.

On Saturday, the government officials held a meeting with poultry farmers on what measures can be taken to bring the outbreak under control.

"We discussed declaring either Bhaktapur district or the whole capital valley as the emergency zone, in terms of bird flu spread. But we are yet to reach a decision," officials of the Department told Xinhua.