For the Nuba people, it means the first real chance of peace after almost two decades of suffering, in which they have often been caught in the middle of the country's long-running civil war.

But even if the agreement - which is renewable every six months - sticks, it is far from clear that it will help in ending the conflict, which has claimed an estimated two million lives.

The Nuba people number about one million, but they have always occupied a precarious position in Sudan.

Their mountainous homeland straddles the frontline of the civil war between the mainly Christian and animist south and the mainly Islamic north.

Harsh treatment

Many Nuba serve in the Sudanese army controlled from Khartoum, but they have long complained of discrimination and exploitation at the hands of the Arabs who dominate northern Sudan.

Such complaints lay behind their decision in 1985 to throw in their lot with the mainly Christian and animist rebels of the Sudan People's Liberation Army, the SPLA, in their fight for greater autonomy from Khartoum.

But the Nuba have paid a heavy price, particularly since Islamic hardliners took power a decade ago.

Aid deficit

Thousands of Nuba fled the region in the 1990s, because of what human rights groups describe as ethnic cleansing ordered by the Khartoum Government.

Their situation was made worse because they were excluded from United Nations aid operations.

The ceasefire agreement in Switzerland will be welcome to Nuba leaders, who had feared their demands would be ignored in any talks between Khartoum and the SPLA on ending the 19-year-old civil war.

But this is not a final settlement - and as long as the conflict continues elsewhere, life for the Nuba is unlikely to get much easier, because their isolated geographical position will make it very difficult to get humanitarian aid and other assistance through.