In its annual health report for 2010, the U.N. body said some countries had made impressive gains, although others may struggle to meet some of the 2015 targets.

With five years remaining to the MDG deadline in 2015 there are some striking improvements, said the report, which is based on data collected from WHO's 193 member states.

Liberia, Sierra Leone, Mozambique and Rwanda had made progress on child mortality despite facing difficulties, WHO said.

However the group said global results mask inequalities between countries, and some nations' progress had been slowed by conflict, poor governance or humanitarian and economic crises.

The Millennium Development Goals were set in 2000 by 189 heads of state seeking to drive global policy to tackle poverty, hunger, ill-health and lack of access to clean water, among other things.

The key findings of WHO's report were that:

* Fewer children are dying, with annual global deaths of children under five falling to 8.8 million in 2008 - down by 30 percent since 1990;

* The estimated percentage of underweight children under five has dropped from 25 percent in 1990 to 16 percent in 2010;

* The proportion of births attended by a skilled health worker has increased globally, but in the Africa and southeast Asia fewer than 50 percent of all births were attended;

* New HIV infections have declined by 16 percent globally from 2001 to 2008. In 2008, 2.7 million people contracted the human immunodeficiency virus which causes AIDS, and there were 2 million HIV/AIDS-related deaths;

* Existing cases of tuberculosis are declining, along with deaths among HIV-negative tuberculosis cases;

* The world is on track to achieve the MDG target on access to safe drinking water, but more needs to be done to achieve the sanitation target.

The water and sanitation goals call for the proportion of people without sustainable access to safe drinking water and basic sanitation to be halved by 2015 from levels in 2000.

The WHO report found that the percentage of the world's population with access to safe drinking water had increased from 77 percent to 87 percent, a rate of improvement it said would hit the MDG target if it keeps up.

In low-income countries, however, the annual rate of increase needs to double in order to reach the target and a gap persists between urban and rural areas in many countries, the report said.

On sanitation, the progress was less good: in 2008, 2.6 billion people had no access to a hygienic toilet and 1.1 billion were still defecating in the open, it said.

Poor sewerage can spread dangerous infections such as viral hepatitis and cholera.

The slowest improvement has been in Africa, where the percentage of the population using toilets or latrines increased from 30 percent in 1990 to 34 percent in 2008.