By Opheera McDoom

KHARTOUM (Reuters) - Khartoum must sit down to Darfur peace talks by the end of the year or face all-out war, the leader of the rebel Justice and Equality Movement (JEM) who launched an unprecedented attack on the capital this month said.

In an interview on Sunday, Khalil Ibrahim, who has a $250,000 (128,000 pound) price on his head after the attack on Khartoum, in which more than 200 people were killed, also urged Egypt to release three JEM officials it arrested in Cairo afterwards.

"Within this year, we have to end the suffering of our people of Darfur either by war or by negotiating a political solution," he told Reuters by satellite telephone.

"Whichever the government accepts we will do."

The rebels were only stopped at the bridges over the Nile to the heart of Khartoum from the western suburb of Omdurman, a few kilometres from the army headquarters and the presidential palace on May 10.

It was the first time rebels from Sudan's marginalised regions managed to bring their war to the capital.

The attack was condemned internationally and by most political parties inside the country.

"There will be no peace in Khartoum without peace in the marginalised regions, in Darfur," Ibrahim said, warning he would attack the capital again if the government chose war instead of talks.

"We are people of one nation," he said. "Part of us cannot enjoy peace in Khartoum while others are dying. Either we are all at war or we are all at peace."

OIL MONEY

International experts estimate 200,000 have died in Darfur, with 2.5 million driven from their homes. Washington called the conflict genocide, a term European governments are reluctant to use, but which has sparked a massive U.S.-led activist movement.

Khartoum blames the Western media for exaggerating the conflict and puts the death toll at 10,000.

Khartoum has boomed from a massive injection of foreign investment and rising oil revenues since signing a 2005 north-south peace deal ending a separate conflict. That deal did not cover Darfur. Analysts fear investors will think twice about pouring money into the capital with the threat of attack.

Sudan had asked world leaders to list JEM as a terrorist movement and extradite all members to Khartoum for trial.

Ibrahim urged Egypt to release three JEM officials they arrested after the assault. "They are civilians not military."

Darfur's peace process has stalled under joint U.N. and African Union mediation, appointed at the beginning of 2007. Ibrahim said the two envoys, Jan Eliasson and Salim Ahmed Salim, should resign.

"These men should be changed and a serious mediation who is interested to bring peace (should be appointed)," he said. "The international community failed to find a solution ... so they left us no choice other than to go to war." 

Ibrahim's JEM is an Islamist movement whereas other factions from Darfur's fractured rebels support secularism. They launched their revolt in early 2003 accusing central government of neglecting the remote west.

JEM's agenda has always been more national while other groups want a fairer deal for Darfur. Analysts agree with Khartoum's assessment that JEM's newly acquired military power was provided by Chad. In the early part of the conflict, JEM was militarily weaker than the other main Darfur rebel Sudan Liberation Army (SLA).

Sudan cut diplomatic relations with Chad after the assault. Chad denies links to JEM.