GENEVA -- The top World Health Organization (WHO) official warned on Monday that while poor countries faced ill health from having too little, richer ones faced high risks from over-consumption.

Gro Harlem Brundtland, the WHO's director-general, told the World Health Assembly here that poverty, unsafe water, unsafe sex and under-nutrition in poorer countries were only one part of the global risk factor.

"On the one side are the millions who are dangerously short of the food, water and security they need to live," she told delegates from the 191 member countries of the Geneva-based UN health agency.

"On the other side are the millions who suffer because they use too much. All of them face high risks of ill-health," she said on the opening day of the World Health Assembly, scheduled to run until Saturday.

But she also warned that blood pressure, cholesterol, tobacco- related diseases and obesity were becoming more common in developing countries where they posed a "double burden" on top of infectious diseases.

According to AFP, delegates at the meeting are due to tackle issues such as bioterrorism, access to drugs for poor countries, the aids epidemic, mental health, the eradication of smallpox, tuberculosis, malaria and polio.

Brundtland, who has made tobacco control one of her priorities, said many countries had tightened their national tobacco control policies but added that many were still not doing enough.

She urged countries to redouble their efforts in negotiations under way to draw up a global treaty by May 2003, aimed at cutting the estimated four million deaths annually from smoking-related ailments.

"For the sake of future generations we cannot afford complacency," she said.

But the WHO official said progress on alcohol was much further behind, adding that new data due to be published in a key report later in the year showed that its burden on morbidity and mortality had significantly increased since 1990.

WHO also calls for policies to improve access to essential health care for all, as well as urging pharmaceutical companies to reform pricing structures and to invest more in drugs to fight aids, malaria and other infectious diseases, she said.

Leading humanitarian group Medecins Sans Frontieres (MSF, doctors without borders) urged the WHO to take more of a leadership role, especially on research and development of drugs for "neglected diseases", and in the area of trade rules and access to badly-needed drugs.