BEIJING: China has discovered eight people with mutated versions of H1N1 flu but drugs are still effective against the new strains, a senior health official told the official Xinhua news agency.

Shu Yuelong, director of the Chinese National Influenza Centre, said the first mutated strain of the (A)H1N1 virus was detected in June in a case imported from Britain and a similar strain was detected three months later in the eastern province of Zhejiang.

"Mutations are almost inevitable in influenza viruses," Shu told Xinhua Wednesday.

The mutation detected recently was an isolated case and the cases were not connected, Shu said.

Scientists fear that mutations in flu viruses could cause more virulent and deadly pandemic flu.

"This kind of mutant virus has been found in patients with slight and heavy symptoms as well as those who have recovered. The virus has not widely spread so far," Yu Hongjie, an expert from the Chinese Centre for Disease Control and Prevention, told Xinhua.

The World Health Organisation said on Friday that a mutation had been found in samples of the H1N1 flu virus taken following the first two deaths from the pandemic in Norway.

It said a similar mutation had been observed in Brazil, China, Japan, Mexico, Ukraine, and the United States, as early as April.

However, it stressed that the mutation did not appear to cause a more contagious or more dangerous form of A(H1N1) influenza and that some similar cases observed elsewhere had been mild.

Hong Kong's health department has reported one case of the Norwegian mutation, in a young boy.

China has reported 53 deaths out of nearly 70,000 confirmed H1N1 flu cases but last week ordered more accurate reporting of fatalities after a medical expert said deaths were being deliberately underplayed.

At least 6,770 people have died from H1N1 flu out of more than half a million cases reported since the virus was first uncovered in Mexico and the United States in April, according to WHO figures.

The WHO estimates that some 250,000 to 500,000 people die every year from standard seasonal variants of H1N1 flu. - AFP/de