The World Health Organization on Wednesday confirmed six human cases of bird flu in Indonesia, raising the global toll of human cases to 121. Five members of a family were infected reawaking fears of possible human-to-human transmission of the virus.

A statement from a WHO spokesperson said, "There are six confirmations. One from Surabaya and five others from Medan. One from Medan is still alive."

The confirmation of eight cases of bird flu in a family has triggered fears among health agencies worldwide. An Indonesian Health Ministry official played down fears after he said there was no human-to-human transmission. He said the multiple cases in the family were transmitted through poultry and other animal products.

Contrary to the government statement, a senior agriculture official who preferred to remain anonymous said, "There is a big question mark. Blood samples from all kinds of animals from chickens, ducks, geese, birds, pigs, cats and dogs turned out negative so far. Manure has also been checked. The result is negative."

World Health Organization officials have sent a team of experts to Medan, in the North Sumatra province where the cases were identified. The U.N. health agency said it was closely monitoring the virus, in case of any possible mutation which could lead to transmission between humans. Any such development can result into a global pandemic that could claim millions of lives.