"Sudan is in a state of high tension at the moment, and we face a dangerous month ahead," Sudan expert Alex de Waal, said. "Parts of Darfur are again in flames, with the worst fighting in the region since the beginning of 2008."
The fighting, which started in mid-January around Muhajiriya in South Darfur, has forced thousands of civilians to flee their homes, with many heading north of the town, according to the UN Office for the Coordination of Humanitarian Affairs (OCHA).
"They are displaced, but a lot of them are still on the move," said Zeljko Nikolich, OCHA humanitarian affairs officer in El-Fasher, capital of North Darfur state. "A lot of them are temporarily settled in places."
OCHA, he said, had received reports of six trucks - each carrying 30-50 people - arriving in El-Fasher from Muhajiriya. Another 50 families had arrived in the town of Shangil Tobay, he added, quoting Oxfam, while 400 more families were en route.
Citing a report by the humanitarian coordinator of a faction of the Sudan Liberation Army (SLA), Nikolich said another 300 households had arrived in the Wadaah area, almost 100km north of Muhajiriya. Four hundred others were in Khazan Djedid village - en route to Wadaah.
The SLA faction is led by Mini Minnawi, who became a presidential adviser after signing a peace deal with the government in 2006.
OCHA could not verify the numbers because of insecurity, Nikolich said, adding that four trucks carrying displaced people had arrived in Dar El Salam, along the border between North and South Darfur states.
Another aid worker in Nyala, who requested anonymity, told IRIN on 27 January: "People have been displaced, but we do not know the number yet. We are trying to send a team to Muhajiriya on [29 January] to make an assessment."
The hostilities began in Muhajiriya, 80km east of Nyala, capital of South Darfur state. The town was taken over by JEM rebels from Minnawi's government-aligned group after a battle on 15 January.
Vowing to recapture the town, the army bombed the area and sent ground troops to fight JEM, according to the joint UN-African Union peacekeeping mission, UNAMID.
On 24 January, for example, a government military aircraft dropped two bombs over a camp for displaced people in Muhajiriya, killing one child and damaging 13 houses. Continued fighting in the town has since forced about 3,000 people to camp near UNAMID's base.
UN Secretary-General Ban Ki-moon has condemned the violence, saying continued military action threatens civilian lives and jeopardises efforts to reach a durable peace.
Rodolphe Adada, the Joint UN-AU Special Representative in Darfur, warned that increased insecurity in Darfur would affect the delivery of vital humanitarian aid.
"I call upon all warring parties to instantly cease hostilities and end this cycle of violence that would only add to the suffering of the people of Darfur," Adada said.
The security situation in the area has remained tense, with ground and aerial bombing continuing approximately 9km from El Fasher, UNAMID said on 27 January.
JEM deputy chief of staff, Suleiman Sandal Hagger, told IRIN the government had also bombed JEM positions near El-Fasher, in Wadi Hawar and around Muhajiriya. The area was reportedly calm, however, on 28 January.
"Now the situation is calm, but still the Sudan troops are near us, not far from the places where we are," Sandal said by satellite phone from Darfur. "At any time, [fighting] is imminent."
A Sudanese army spokesman declined to comment, but the government has argued it is acting in self-defence, to maintain security and stability in Darfur and to protect aid convoys from bandits.
De Waal said fighting had escalated ahead of an expected decision by the International Criminal Court on possible charges related to war crimes in Darfur against President Omar al-Bashir.