US fastfood giant KFC has said it has closed almost all its outlets in Vietnam while it changes its menu to provide more fish after the outbreak of bird flu in the country hurt sales of its fried chicken.

The company, owned by fastfood giant Yum! Brands, closed eight KFC outlets in Ho Chi Minh City and plans to reopen them at the end of the week with a different menu. Instead of its familiar fried chicken, the chain is to offer fish burgers, reported Reuters.

“It has been very hard for us,” Nguyen Chi Kien, KFC’s Vietnam deputy country director, told Reuters.

The company operates nine restaurants in southern Vietnam, but has larger chains in other countries affected by the disease.

KFC has more than 3,000 restaurants in Asia, a third of which are in Japan. More than 900 outlets are in China and Hong Kong, while there are more than 300 each in Thailand and Malaysia. The company also has 130 outlets in the Philippines.

Millions of chickens have died of the disease or been culled in Thailand and Vietnam, two of the worse hit countries.

Malaysia and the Philippines are so far free of the disease, but are on heightened alert as the disease spreads across Asia.

China has confirmed an outbreak of the virus in its duck population, but the disease does not appear to have yet spread to poultry.