The agency, the United States Comittee for Refugees, said that the fight for control of southern and central Sudan had killed one in five of the southern Sudanese population - either by warfare, war-induced famine or direct government or rebel policies.

Jeff Drumtra, a senior policy analyst with the organisation said the death count was "a fairly conservative estimate".

Many children have known nothing but war

More than 70,000 people died in the first six months of this year alone the report said.

The figures were compiled from dozens of documents and reports by many of the 40 aid agencies operating in Sudan.

About 80% of southern Sudan's estimated five million people have been displaced at one time or another since 1983 by fighting between rebels from the animist and Christian south, and forces loyal to the government of the Arab and Islamic north.

The report said 350,000 people were also living as refugees in neighbouring countries.

Atrocities

The report said that both the government and rebel forces had committed atrocities against the local population.

Fighting hampers relief efforts

But it blamed the former for the bulk of the human rights abuses.

"Sudan's civil war has been characterised by an incremental ferocity that has left untouched practically no one in southern Sudan," it went on.

The government had systematically blocked food supplies to the south, attacked villages and driven large groups of people to areas where they could not survive, it said.

"These are not people killed in crossfire," said Mr Drumtra.

"It's a very deliberate strategy on the part of the government of Sudan to depopulate large parts of southern Sudan."

"What is going on in Sudan, and what has been going for the past 15 years is virtually unprecedented in terms of the devastation to human lives, property and society in the south," he said.