HIV/AIDS infection rates are growing among intravenous drug users, prostitutes and gay men around the globe but they are often viewed as outcasts and refused treatment, according to a report issued on Thursday.

The report, from the International Federation of Red Cross and Red Crescent Societies, also called on governments and humanitarian agencies to pay more attention to AIDS in their response to natural disasters and armed conflicts.

"HIV is a long-term and complex disaster on many levels ... For marginalised groups across the world - injecting drug users, sex workers and men who have sex with men - rates are on the increase," said the Geneva-based humanitarian agency.

Those groups, living on the fringes of society in many countries and especially in the developing world, "often face stigma, criminalisation and little, if any, access to prevention and treatment services," it added.

The 248-page study, an annual World Disasters Report, gave no new figures for AIDS sufferers but cited United Nations statistics that 2.1 million died from the disease last year.

The Federation said the HIV virus was at the root of a rolling social crisis across southern Africa.

Its officials told a news conference the recent violence in Zimbabwe - where until recently the battle against AIDS had benefited from a widespread treatment network - could disrupt medical care and make that situation worse.

"We must not let what we have achieved be put into reverse," Federation specialist Mukesh Kapila said. The body's deputy secretary general Ibrahim Osman said it would help the Zimbabwe Red Cross double the HIV sufferers it supports to 260,000.

The Federation said it centred its 2008 World Disasters Report on the immune-destroying disease rather than floods or earthquakes because for many communities the epidemic "is undoubtedly a disaster."

"Government services are overwhelmed by the need for support and treatment, stigma still prevents access for many, even where services exist, and communities are devastated by its effects," it said.

There were 405 natural disasters worldwide last year, compared to 423 in 2006, the Federation said. Those killed just under 17,000 people, the lowest annual figure for a decade, but the numbers affected rose by 40 percent to 201 million.