Khartoum: Darfur rebels fought Sudanese troops in a suburb of Khartoum on Saturday in a bid to seize power, but the government said the attack on the capital had been defeated.

It was the first time fighting had reached the city in decades of conflict between the traditionally Arab-dominated central government of Africa's biggest country and rebels from peripheral regions that complain of neglect.

Heavy gunfire and artillery shook Omdurman, across the River Nile from the heart of Khartoum. Helicopters and armoured vehicles headed for the fighting and an overnight curfew was declared.

"The main aim of this failed terrorist sabotage attack was to provoke media coverage and let people imagine that they had the ability to enter Khartoum," Mandour Al Mahdi, political secretary of the ruling National Congress Party told state television.

"Thank God this attempt has been completely defeated. Some high level JEM commanders were killed," he said, referring to the Darfur Justice and Equality Movement (JEM) rebels.

Sudan accused neighbouring Chad of backing the rebels, who made a lightning advance across some 600 km (400 miles) of desert and scrub between Darfur and Khartoum. A top official said the attack destroyed any chance of peace talks.

State television showed pictures of corpses, blood and burned vehicles in the streets. It displayed what it said were rebel prisoners, including two who confessed to the camera. One looked badly beaten.

Witnesses said gunfire continued in Omdurman's western outskirts.

The rebels dismissed the government version of events and said fighting was still going on in their attempt to oust President Omar Hassan Al Bashir.

"We are in Omdurman, we are in Khartoum north. This is not something that is going to be finished in a few hours," JEM official Al Tahir Al Faki told Reuters from Britain. "There is an imbalance of power and wealth, we have to sort this out."

Khartoum state is home to around 8 million of the 38 million people in a country bigger than Western Europe.

Sudan's economy, driven by increasing oil production, has grown rapidly since a peace deal between north and south ended one civil war in 2005, but that agreement did not cover the conflict that erupted in Darfur five years ago.

International experts estimate some 200,000 people have died and 2.5 million been made homeless in Darfur since mostly non-Arab rebels took up arms.

The United States describes the conflict in Darfur as genocide, but Khartoum rejects that term and says only around 10,000 people have been killed. Sudan is a close ally of China, a big oil industry investor and its main arms supplier.

Western countries, pushing for peace talks, have accused Khartoum of dragging its feet over deployment of a 26,000 strong UN-African Union peacekeeping force in Darfur. Fighting has intensified there in recent months.

Presidential Advisor Mustafa Osman Ismail ruled out any chance of peace talks with JEM after the attack on Khartoum.

"From this day we will never deal with this movement again other than in the way they have just dealt with us," he said on Al Jazeera television.

The United States urged both sides to cease hostilities.