The World Health Organisation (WHO) has urged all sexually active gay men to take antiretroviral drugs to reduce the spread of HIV.

The organisation says the move may help prevent a million new HIV infections over 10 years.

Officials warn that the rates of HIV in this group remain high across the globe. But activists suggest this could discourage the use of condoms, one of the best methods to stop the virus spreading.

In a report, WHO said men who have sex with men are 19 times more likely to have HIV than the general population. 

Health experts say offering antiretroviral drugs to all at-risk men, an approach known as pre-exposure prophylaxis (PrEP), will provide an additional way to prevent infection, together with condom use.

HIV experts estimate that globally, HIV incidence among gay men could be cut by 20 to 25 per cent through PrEP, averting up to one million new infections in this group over 10 years.

When taken consistently by people at high risk, studies show the medication can reduce the chances of getting HIV by up to 92 per cent.

And scientists say encouraging this group of men to take these pills could lead to a 25 per cent reduction in new cases across the globe.

Dr Rosemary Gillespie, of the Terrence Higgins Trust, said: "We already know if someone has HIV, using treatment drastically reduces the likelihood of them passing it on, as does using condoms.

"The idea of treatment as prevention is not new, but the idea of extending treatment to HIV-negative people from high-risk groups is.

"Pre-exposure prophylaxis is an exciting approach, and likely to be one of a number of ways in which we can reduce the spread of HIV in the future.

"However, we need to evaluate how effective it will be in preventing HIV among gay men.”

"The reason we are adding this to our prevention choices for men who have sex with men is that we have these very worrying increases in HIV incidence,” added Rachel Baggaley, coordinator of the WHO’s department for HIV/Aids.

‘Progress threatened’

And while the number of people dying of Aids-related causes is falling sharply, WHO says key populations need more attention.

According to the report, transgender women are almost 50 times more likely to have HIV than other adults, a level similar to that seen among people who inject drugs. And sex workers are 14 times more likely to have HIV than the general population.

"Dr Gottfried Hirnschall, of WHO said: "Failure to provide services to the people who are at greatest risk of HIV jeopardises further progress against the global epidemic and threatens the health and well-being of individuals, their families and the broader community.”

Some 35.3 million people worldwide are infected with HIV, but the rising number of patients reflects great strides in recent years in developing sophisticated HIV tests and combination Aids drugs and getting them to many of those who need them to stay alive.

As a result, the annual Aids death toll is falling, dropping to 1.6 million people in 2012 from a peak of 2.3 million in 2005.

New HIV infections are also steadily declining, and dropped by a third in 2013 from 2011.

Yet figures show the key high risk populations continue to have high infection rates, and appear to be hard-to-reach in terms of getting the right prevention messages, or getting them the testing and treatment health services they need.

WHO says in many countries, gay men, sex workers and other marginalised groups are left out of national HIV plans and excluded by discriminatory laws and policies.

But none of these people live in isolation; sex workers and their clients have husbands, wives and partners. Some inject drugs. Many have children. Failure to provide services to the people who are at greatest risk of HIV jeopardises further progress against the global epidemic.

The WHO report, released ahead of the International Aids Conference in Melbourne, Australia on July 20, said by the end of 2013, around 13 million people worldwide were taking ARVs.

This has led to a 20 per cent drop in HIV-related deaths between 2009 and 2012, it said.