By Ania Lichtarowicz BBC health reporter

The aim of the project is to widen the availability of HIV drugs

Latest figures, presented on the eve of the 25th international Aids Conference in Bangkok, show that nearly twice as many people in developing countries are receiving antiretroviral drugs compared with two years ago.

However progress has been slower than hoped.

The WHO wanted to get half a million people on treatment by now - currently they are about 60,000 short.

There is also a significant shortage of trained health care workers - at least 100,000 are needed to make the scheme successful.

The ultimate goal is universal access, three by five is an emergency interim goal to get people their help as soon as possible Dr. Jack Chow, WHO Aids division

Dr Jack Chow, from the WHO Aids division, says the Three by Five target has to work.

"We are going to do it. For those who are living with the virus today and who need help it is essential. It is vital that they receive the antiretrovirals as soon as possible.

"Eight thousand people are dying everyday. The ultimate goal is universal access. Three by Five is an emergency interim goal to get people help as soon as possible."

Challenges ahead

The project has changed attitudes towards treating people in developing countries - just a few years ago many doctors thought large scale treatment programmes would not work in resource poor areas.

The scheme, coupled with the cost of drugs dropping by more than 90%, has changed the debate to not if, but when, antiretrovirals will be widely available everywhere.

Despite a shortfall of more than $60m, the Three by Five strategy is under way.