By Karen Allen
BBC News health correspondent
A target to get three million people in the poorest parts of the world onto anti-Aids drugs by the end of the year will almost certainly not be met.
HIV is a major problem in the developing world
World Health Organisation figures reveal just one million people are receiving life saving treatment.
Senior WHO figures say that is double the number who were on drugs when the target was set in December 2003.
But 40 million people are infected with HIV globally, with around six million in the developing world seriously ill.
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.
But with six months to go until the deadline expires, WHO officials are clearly disappointed that more progress has not been made.
They argue that in the past few months there has been a huge escalation in efforts to get medicines to those who need them.
Barriers to access
But obstacles remain. There are not enough single pill versions of drugs, there are very few aids medicines for children and technical problems with supplies persist.
Many countries also lack a co-ordinated strategy to get drugs out and sufficient 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.
And a WHO progress report says an additional $18bn above what has already been pledged will be required, to finance the drugs rollout over the next three years.
WHO Director-general Lee Jong-Wook said: "This is the first time that complex therapy for a chronic condition has been introduced at anything approaching this scale in the developing world.
"The challenges in providing sustainable care in resource-poor settings are enormous, as we expected them to be.
"But every day demonstrates that this type of care can and must be provided."
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."