|The Justice and Equality Movement (JEM) leaders called al-Bashir's ultimatum a 'declaration of war'. [AFP]
Sudan's president has said his government will withdraw from peace talks in Doha and organise its own negotiations if no agreement with the rebels in the western Darfur region is reached this week.
Omar al-Bashir's comments on Wednesday prompted angry response from one rebel group in the country's war-torn western region - the Justice and Equality Movement (JEM) - which called the remarks "a declaration of war".
"If we reach an agreement tomorrow, praise be to God," al-Bashir told thousands of his supporters in Nyala in a speech broadcast live on state television.
"But if there is no agreement, we will withdraw our negotiating team and the talks will then be held in Darfur. We will fight those who choose to take up arms, but we will sit next to those who want development."
Mohammed Adow, Al Jazeera's correspondent in Khartoum, said: "The president's comments just show frustration with the long period the Doha peace process has taken."
He said the government views the slow progress as "lack of readiness on the part of the rebel movement to come to the negotiating table".
The decision by al-Bashir to give much attention to development in Darfur rather than negotiations with the rebels has been criticised by opponents who feel they are being sidelined and yet "they are key to any peace process for Darfur," said our correspondent.
Al-Bashir's ultimatum came as his special adviser on Darfur, Ghazi Salaheddine, was expected in the Qatari capital on Wednesday to push the talks, according to Sudan's official SUNA news agency.
Ahmed Hussein Adam, a spokesperson for JEM, told the AFP news agency the ultimatum "undermines the efforts of the international community and of the mediation to resolve this conflict through political means".
"JEM is committed to reach a fair settlement of the conflict, which is why we are here in Doha," he said. "If the Sudan government leaves Doha, we cannot have an agreement with ourselves."
The Doha peace talks suffered a major blow earlier this week when Darfur rebels clashed with Sudanese government troops three days after announcing they had resumed ceasefire negotiations.
The Sudanese government said its forces killed 40 rebels in the fighting in northern Darfur and that two of its soldiers were also killed and 13 others injured.
Deadly violence in Darfur since December 10 has displaced around 32,000 people, according to UN estimates.
"These clashes are deplorable and demonstrate the importance of a ceasefire... If the violence escalates, the general atmosphere in the negotiations will deteriorate," Djibril Bassole, the UN-African Union chief peace negotiator for Darfur, told the AFP news agency on Tuesday.
Bassole said he would try to persuade the different parties not to abandon the peace process, even if an agreement was not reached in the coming days.
"I am among those who want a swift and satisfactory solution. But mediation by someone with a stopwatch in his hand is not good mediation," he added.
Darfur has been gripped by a civil war since 2003 that has killed 300,000 people and displaced another 2.7 million, according to UN figures. Khartoum says 10,000 people have died in the conflict.