The Ministry of Agriculture and Rural Development's Plant Protection Department has asked enterprises to return the goods instead of allowing it to be fumigated as usual. The feed was specially prepared for the breeding industries.

The department said Vietnam was free of the invasive pest. It added that it had told Indian suppliers to fumigate the feed before it was sent because it was such a large quantity that would have been too difficult to fumigate.

The feed is currently being stored at the ports of Hai Phong and Sai Gon.

Chairman of the Vietnam Feed Association Le Ba Lich said stock feed was often imported and the department had previously allowed fumigation if termites were detected.

"But the goods have been refused entry this time. About 20 enterprises will suffer total losses of US$35-40 million if the goods have to be returned," Lich said.

He added that enterprises would receive no compensation from partners or relevant authorities.

Hoang Trung, deputy director of the Plant Protection Department, said the termites (trogoderma granarium) were listed among the most 100 invasive insects in the world and could seriously affect Vietnam's agricultural exports of rice and other farm products.

Previously, about 5,745 tonnes of stock feed from India was fumigated successfully after being found to contain traces of termites.

The ministry sent warnings to Indian suppliers about the need for fumigation before they exported it to Vietnam.