A 20-year-old woman in Indonesia is critically ill with bird flu, health officials said Monday, becoming the 85th human case in the country worst hit by the deadly virus.

The woman was being treated in a hospital in Surabaya, the country´s second-largest city, said an official from the Bird Flu Information Centre who declined to be named.

Indonesia has suffered 64 bird flu fatalities since its first human case was detected in the middle of 2005, the world´s highest toll.

The critically ill woman was admitted with bird flu symptoms six days ago and had a history of close contact with poultry, hospital official Teguh Silfaranto told AFP.

Sick birds are so far the main source of infection in Indonesia, whose government has banned people in Jakarta, the capital, from the popular practice of keeping poultry in back yards.

The global spread of the deadly H5N1 strain of bird flu is being closely tracked.

Egypt said late Saturday that a four-year-old boy had become its 24th human case. Laos announced its first confirmed human death from the strain, a 15-year-old girl, last week.