The effects of a decade of fighting in the Democratic Republic of Congo is continuing to kill about 45,000 people each month - half of them small children - in the deadliest conflict since the second world war, according to a new survey.

The International Rescue Committee said preventable diseases and starvation aggravated by conflict had claimed 5.4m lives since the beginning of the second Congo war in 1998, equivalent to the population of Denmark.

Although the war officially ended in 2002, malaria, diarrhoea, pneumonia and malnutrition have continued to claim enormous numbers of lives in part because fighting continues in the east of the country.

The study of 14,000 households across Congo between January 2006 and April 2007 found that nearly half of all the deaths were of children under the age of five, who make up only 19% of the population.

"The majority of deaths have been due to infectious diseases, malnutrition and neonatal- and pregnancy-related conditions," the survey says.

"Increased rates of disease are likely related to the social and economic disturbances caused by conflict, including disruption of health services, poor food security, deterioration of infrastructure and population displacement. Children are particularly susceptible to these easily preventable and treatable conditions."

Congo has endured two foreign invasions and protracted civil war since the aftermath of Rwanda's genocide spilled across the border in 1994 with an influx of more than a million Rwandan Hutu refugees.

The years of conflict resulted in millions of people fleeing their homes, sometimes to live for years in forests where many died, and the collapse of what infrastructure still remained after decades of neglectful rule under Mobutu Sese Seko.

Those who returned home found water sources, health clinics and farms destroyed. Marauding bands of armed men were responsible for mass rape, particularly in the east of the country, which made it much more difficult for women to venture into fields to grow food.

"When war destroys a country's economy and infrastructure, there's no quick fix," said Dr. Richard Brennan, one of the survey's authors.

"Significant improvement in Congo's health and mortality will require years of unwavering commitment from the government and the international community and substantial financial investment. Sadly, the humanitarian crisis in Congo continues to be overlooked and funding remains disproportionate to the enormity of need."

The IRC said that a peace deal in the eastern province of North Kivu, where continued fighting has displaced hundreds of thousands of people in recent months, is also crucial to curbing the rising death toll.

There was hope today that the conflict in the east might finally be drawing to a close after the government and armed groups were reported to be ready to sign a peace agreement. But the deal apparently did not directly address how to deal with two of the most important armed factions - that of the rebel Tutsi general, Laurent Nkunda, who is wanted for war crimes, and the Rwandan Hutu group that has been a leading cause of instability.

Congo is one of 11 countries where 20% of children die before the age of five according to a Unicef report released today. A child born in Sierra Leone has the lowest chance of surviving until the age of five. The report, the State of the World's Children, says nearly 9.7 million children under five died worldwide last year from disease or lack of food.

In Sierra Leone, which is still recovering from an 11-year civil war, the child mortality rate was 270 deaths per 1,000 births. The average rate in developed countries is six deaths per 1,000 births.

Twenty-eight of the 30 countries with the highest child mortality rates are in sub-Saharan Africa. But Unicef said there have also been successes on the continent. Mozambique has seen a 41% drop in child mortality since 1990.