India has the largest number of people living with the Human Immuno-deficiency Virus outside South Africa, and most  infections were acquired sexually, though drug use through injection dominated some states in the country's north-east, a fact sheet issued by UNAIDS has said.

 'In this area, infection levels of 60 to 75 per cent have been found among injecting drug users using non-sterile injecting equipment,' the UN body said.

In many parts of India, HIV transmission through sex between men is also a major concern, the fact sheet said, adding that research showed some men who had sex with men may also have sex with women.

The sheet said in China, 10 million people may be infected with HIV by 2010 unless effective action was urgently taken. 'The virus has spread to all 31 provinces, autonomous regions and municipalities, yet each area had its own distinctive epidemic pattern,' it said.

Asia is faced with a narrow window of opportunity to prevent AIDS from having a more severe impact on the region, the sheet warned. The region includes the world's most populous countries -- China and India -- with 2.25 billion people between them.

'In both countries, national HIV prevalence is low --  0.1 per cent in China and between 0.4 per cent and 1.3 per cent in India. But a closer focus reveals that both have extremely serious epidemics in a number of provinces, treritories and states,' the sheet added.