Oct 9 (Reuters) - United Nations aid workers struggled to deliver food to thousands of civilians cut off by fighting in Congo's North Kivu province on Tuesday as rebel soldiers battled government troops after abandoning a ceasefire.

The renewed clashes between fighters loyal to renegade general Laurent Nkunda and the Congolese army threatened to worsen an already dire humanitarian situation in the eastern border province of Democratic Republic of Congo.

Here are some details about the fighting in the east.

* ORIGINS OF THE CONFLICT:

-- The roots of Nkunda's rebellion in North Kivu lie in unhealed ethnic and political wounds that have made the racially mixed eastern Congo a regional tinderbox.

-- The presence of both Tutsi and Hutu rebels there stems from Rwanda's 1994 genocide. The genocide saw 800,000 Tutsis and moderate Hutus killed in 100 days by the Hutu-led government and ethnic militias.

-- It led to subsequent invasions by Rwandan forces that helped ignite the 1998-2003 war in Congo.

-- Nkunda led a revolt in 2004 with around 4,000 soldiers and briefly captured Bukavu, the capital of neighbouring South Kivu. He still faces an international arrest warrant for war crimes allegedly committed during the brief occupation.

-- Following 2006 elections aimed at drawing a line under the 1998-2003 war which killed some 4 million people, President Joseph Kabila promised to bring peace to Congo's east.

-- However in a November 2006 crackdown, United Nations Mission in Congo (MONUC) helicopters and armoured vehicles killed hundreds of Nkunda's fighters, paving the way for a January peace deal. The crackdown was meant to help pacify North Kivu, long a stronghold of militias.

-- Nkunda says he is fighting to protect his Tutsi people in eastern Congo against attacks by the Democratic Forces for the Liberation of Rwanda (FDLR) which control parts of North Kivu and which he says are backed by Kabila's government. This is made up of former Rwandan soldiers and members of the Hutu militias, or Interahamwe, which took part in the Rwandan genocide.

* WHY MORE FIGHTING?:

-- Analysts believe Congo's President Kabila may be trying to crush Nkunda militarily, anxious to pacify the vast, mineral-rich former Belgian colony after his victory in landmark elections late last year. -- Nkunda has turned much of North Kivu province into his personal fiefdom. His fighters have battled with the United Nations-backed Congolese army there, forcing thousands of civilian refugees to flee their homes.

* CEASEFIRE NOW OVER:

-- U.N. mediators announced a limited ceasefire on Sept 6 after nearly two weeks of fighting in the volatile province as thousands of Tutsi fighters loyal to Nkunda appeared to have turned the tide on government forces, and were pressing ahead towards the provincial capital Goma.

-- However, last week the DRC army said it had killed at least 35 fighters loyal to the renegade Tutsi general during a battle just north of Ngungu, west of the provincial capital Goma.

-- Nkunda said on Monday he was abandoning the ceasefire, blaming attacks by the government, which in turn accused him of pushing the country towards war.

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