Vietnam, Thailand and Indonesia will, early next month, double dose of anti-bird flu medicine Tamiflu to test the virus' potential resistance ability, local newspaper Pioneer reported Tuesday.

In Vietnam, the test, under which the Tamiflu dose is to increase to 150 mg from current 75 mg, will be conducted in the two Tropical Diseases hospitals in Hanoi capital and southern Ho Chi Minh City, helping scientists get to know whether bird flu virus strain H5N1 can develop resistance to high dose of Tamiflu or not, the newspaper quoted Nguyen Tran Hien, director of the country's National Institute of Hygiene and Epidemiology, as saying.

The research on potential resistance of H5N1 will be carried out by the three countries for several years, helping them to find out the best treatment method for bird flu patients.

A total of 231 human cases of bird flu infections, including 133 fatalities, have been confirmed in 10 countries, since 2003, according to a statement of the World Health Organization posted on its website on July 20. Countries with high numbers of fatalities include Vietnam with 42, Indonesia with 42, and Thailand with 14.

Vietnam has detected 93 bird flu patients, including 42 fatalities, in 32 localities since the disease started to hit the country in December 2003, the country's Health Ministry said on July 20, noting that it has seen no new human cases of infections since mid-November 2005.