Two more new human cases of H5N1 avian influenza have been confirmed in Cambodia, bringing the number of the cases to 26 so far this year, said a joint statement by the World Health Organization and the Cambodian Health Ministry on Thursday.

A 3-year-old boy from Kampong Speu province and a 29-year-old man from Pailin province -- who died last week -- marked the 25th and 26th confirmed cases of avian influenza this year, the statement said.

"The 3-year-old boy is currently receiving medical treatment at Kantha Bopha Hospital in Phnom Penh, but his condition is critical, " it said.

Both victims had direct contact with sick and dead poultry prior to their illness onset, it added.

Only 12 out of the 26 cases this year survived.

"Avian influenza H5N1 remains a serious threat to the health of all Cambodians and children seem to be most vulnerable and are at high risk," Health Minister Mam Bunheng said.

He urged parents and guardians to keep children away from sick or dead poultry and make sure children wash their hands with soap and water after any contact with poultry.

H5N1 influenza is a flu that normally spreads between sick poultry, but it can sometimes spread from poultry to humans, according to the WHO.

Cambodia sees the worst outbreak of the virus this year since it was first identified in 2004. To date, the country has reported 47 human cases of the virus, in which 33 were killed.