HIV/AIDS is witnessing a resurgence in countries where infection rates were previously stable or declining, the United Nations has said.

The global epidemic continues to grow with 2.9 million deaths and 4.3 million new HIV infections in the past year, the world body reported in its AIDS Epidemic Update, released on Tuesday.

In North America and Western Europe, prevention programmes have often not been sustained and new infection rates have remained the same. In low and middle-income countries, there are only a few examples of rate reductions.

And some countries that had shown earlier successes in reducing new infections, such as Uganda, have either slowed or are now experiencing increasing infection rates.

"This is worrying as we know increased HIV prevention programmes in these countries have shown progress in the past. Uganda is a prime example," UNAIDS Executive Director Peter Piot said.

"This means that countries are not moving at the same speed as their epidemics. We need to greatly intensify life-saving prevention efforts while we expand HIV treatment programmes," he said.

There is increasing evidence of outbreaks among men who have sex with men in India, Pakistan, Nepal, China, Cambodia, Thailand and Vietnam as well as across Latin America, but most national programmes fail to address the specific needs of these people, the report noted.

The overlap between injecting drug use and sex work in Latin America, Eastern Europe and particularly Asia is also not being addressed. In Latin America, the Caribbean, the Middle East, and North Africa, the surveillance is often weak.

"It is imperative that we continue to increase investment in both HIV prevention and treatment services to reduce unnecessary deaths and illness from this disease," UN World Health Organisation Acting Director-General Anders Nordstrwm said.

"In sub-Saharan Africa, the worst affected region, life expectancy at birth is now just 47 years, which is 30 years less than most high-income countries," he added.

The report showed that 2.8 million, accounting for 65 per cent of new infections, occurred in sub-Saharan Africa, with increases in Eastern Europe and Central Asia where some indications register a more than 50 per cent rise since 2004.

However, there has been decline in infection rates in some countries with changes in young people's sexual behaviour and increased access to treatment and prevention programmes.

But in many countries prevention programmes are not reaching those most at risk, such as young people, women and girls, men who have sex with men, sex workers, injecting drug users, and ethnic and cultural minorities, it added.

Declines in HIV prevalence among young people between 2000 and 2005 are evident in Botswana, Burundi, Kenya, Malawi, Rwanda, Tanzania and Zimbabwe.

In China, some programmes for sex workers have seen marked increases in condom use and decreases in rates of sexually transmitted infections. Programmes with injecting drug users also show progress in some regions.