A flare-up this week in an oil-rich flashpoint in central Sudan is jeopardizing a shaky 2005 peace accord between north and south. That's raising concerns of a return to all-out civil war, even as conflict in the western region of Darfur rages on.
The violence in Abyei broke out this week between Sudanese government troops and southern forces from the Sudan People's Liberation Army. It comes on the heels of a brazen attack by Darfur rebels on Khartoum's twin city, Omdurman, last Saturday – the first such attack on the capital area.
Four Indian oil workers were also taken hostage in Abyei, according to the Indian ambassador, reports the British Broadcasting Corp. The BBC reported that the Justice and Equality Movement (JEM) rebel group from Darfur – which has carried out similar kidnappings of Chinese oil workers and was responsible for last Saturday's attack near the capital – denied responsibility.
Trouble began in Abyei on Tuesday, when southern forces detained a northern soldier and some civilians.
A U.N. official said fighting in Abyei had worsened on Wednesday after a Sudanese government soldier was killed. "That seemed to cause the escalation," the official said, speaking on condition of anonymity.
[A diplomatic] source said an SPLA [former rebel Sudan People's Liberation Army] soldier was killed on Wednesday: "There are gunshots in town, heavy gunfire and mortars."
The  peace agreement created a unity government led by President Omar al-Bashir and his one-time military rival, First Vice President Salva Kiir. It also set up a semiautonomous southern government, led by Kiir, and called for national elections in 2009 and a referendum on independence for South Sudan in 2011.
The Sudanese People's Liberation Movement, which Kiir heads, has accused al-Bashir of multiple breaches of the 2005 accord, including not sharing oil wealth, not pulling troops out of South Sudan, and remilitarizing contested border zones, such as Abyei.
More than two decades of civil war in Sudan have left an estimated 2 million people dead and 4 million displaced, according to the International Crisis Group. The major divide is between the mostly Muslim, Arab north – which dominates the government – and the mostly Christian and animist south. Coveted oil resources in southern Sudan have raised the stakes in the conflict.
In 2003, a separate conflict intensified in the western Darfur region, where government-backed Arab Janjaweed militias have attacked ethnic African civilians. That conflict has left some 300,000 dead, according to the United Nations. It's also turned into what many now see as a proxy war between Sudan and neighboring Chad to its west.
The head of the African Union, Jean Ping, on Thursday urged the leaders of Sudan and Chad to calm tensions, Agence France-Presse reported. More than 200 people were killed in last week's attack and related clashes.
In Sudan, the 2005 peace accord gave the south semiautonomous status. But tension has never fully subsided, particularly in disputed, oil-rich areas along the unofficial north-south border line.
The BBC notes that the disputed status of Abyei was not resolvedin the accord.
Three years after the signing of a peace deal, an administration is yet to be set up in Abyei, which is claimed by both north and south.
"This is indeed one of the most serious issues facing the Comprehensive Peace Agreement between south and north," [UN spokesman Khaled] Mansour told the BBC's Network Africa programme.
He said because of the dispute the town lacked even the most basic services which made the area a "tinderbox".
The agreement stipulates that Abyei is to be guarded by joint units of soldiers from the north and south, according to Reuters.
In mid-March,the International Crisis Group said tensions had subsided when a December agreement saw southern leaders rejoining the unity government after a 2-1/2-month boycott.
But the group warned that "the risk of significant new fighting is growing in the Abyei area."
The group said that the international community was "dangerously disengaged" from the peace agreement, in part because of preoccupation with the ongoing Darfur conflict in the West. It urged the UN and other international players to form a comprehensive policy covering both Darfur and the implementation of the 2005 accord. It specifically recommended:
The UN Mission in Sudan (UNMIS) should increase monitoring of flashpoint areas in Abyei and along the North-South border and negotiate with the parties to create demilitarised zones into which UNMIS forces could deploy and monitor movements of troops to help prevent local flare-ups from escalating.