Secretary-General Kofi Annan today called for the deployment of an advance team in Sudan to prepare for a future United Nations peacekeeping mission as hopes rise of a comprehensive peace agreement to end the 21-year civil war in the south of Africa's biggest country.

In a report to the Security Council, Mr. Annan says the sheer size of Sudan - it is about as large as the whole of Western Europe - and its relative lack of infrastructure means it is important that staff go in as early as possible so they can handle the inevitably daunting logistical challenges.

The planned sectors in a UN peacekeeping mission in Sudan are each the size of Austria, Mr. Annan adds, explaining this will make the tasks of monitoring and verifying any peace deal extremely difficult.

According to the report, the future operation will face many tasks, including the coordination of disarmament, demobilization and reintegration programmes for ex-combatants, the monitoring of ceasefire arrangements, the return of refugees and other humanitarian activities, the organization of elections and the destruction of landmines.

The Sudanese Government and the Sudan People's Liberation Movement/Army (SPLM/A) are holding talks in Kenya to try to reach a full ceasefire and peace agreement. Mr. Annan says in his report that Khartoum and the SPLM/A "at long last are poised to put an end to the long war."

Last month the two sides initialled three protocols aimed at ending the conflict, which has had a devastating impact on Sudan's south. More than two million people have been killed since the war began in 1983, 600,000 fled the country as refugees and another four million people have become internally displaced.

As the war in southern Sudan nears an end, however, a separate conflict in the Darfur region in the country's west - which began early last year - has been described recently by senior UN officials as the world's worst humanitarian crisis.

More than two million people from Darfur are either internally displaced or have escaped to neighbouring Chad because of the fighting between Government-back militia and two rebel groups.

A UN human rights report found that Janjaweed militias, bands of Arab fighters recruited and armed by Khartoum, have committed atrocities against civilians such as murder, rape and the ransacking of villages.

In his report to the Council Mr. Annan says the parties to the conflict in southern Sudan must do all they can to bring an immediate halt to hostilities in Darfur. He also says the recent spate of violence around the town of Malakal in the Upper Nile region of southern Sudan must stop.

Outlining his plan to appoint a Special Representative and two Deputy Special Representatives soon to head up the peacekeeping mission, Mr. Annan stresses it is vital that the international community maintain solid support and investment for the peace process.

"Rebuilding such a vast country will be a huge undertaking," he writes. "Without an enduring, patient commitment there is a real possibility that south Sudan could slide back into conflict and chaos."