By Karen Allen
BBC News health correspondent
Senior figures at the World Health Organization have admitted they will probably fail to meet their target for disseminating HIV drugs.
HIV is a major problem in the developing world
A progress report out on Wednesday will assess whether the target of getting three million people onto the drug by the end of the year is still feasible.
But officials say even if the "three by five" target is missed, it has still served as a catalyst for change.
And they promised efforts to improve access to treatment would continue.
When the WHO announced the "three by five" target in December 2003 - giving Aids drugs to three million people in the developing world by the end of 2005 - it knew that achieving it would be tough.
At the time just 400,000 people were receiving the drugs.
Now as the deadline approaches, the latest progress report is expected to show that although huge strides have been made, the WHO is still way short of its goals.
Figures released by the WHO in January showed the number receiving drugs had increased to 700,000.
Dr Kim Jim, head of the WHO HIV/Aids programme, said: "It is going to be extremely difficult to reach that target, but the point is that we are going to get to three million.
"The scale-up is happening in every single country in the world."
For many countries, the stumbling blocks have been lack of co-ordinated strategy to get drugs out and shortages of staff to monitor patients on the treatment.
There has also been a spiralling demand for anti-retorivirals - as more people receive these potentially life-saving drugs, more and more are coming forward for HIV testing.
With the G8 meeting in Gleneagles next week, the WHO is hoping that the $27bn pledged globally for HIV treatment for the period 2005-2007 will be converted into hard cash.
However, aid agencies have warned that only half the money needed to fund HIV treatment this year has been handed over.
The British government has already pledged to ensure there is universal access to treatment by 2010.
That would mean delivering drugs to 6 million people - double the WHO target.
Gareth Thomas, a minister at the Department for International Development said the UK had played a leading role in rolling out treatments that had probably resulted in 500,000 deaths being averted this year alone.
"As the WHO acknowledge, substantial progress is being made in expanding access to treatment.
"However, we have introduced these treatments from a standing start in many countries that lack facilities and staff.
"We have been urging donors across the world to take a comprehensive response on Aids.
"One that invests in wider health systems, in order to get the medical staff and facilities that makes it possible to prevent and treat Aids.
"We need the drugs but we also need the staff to diagnose patients; test people for drug resistance and undertake extensive prevention work."