Witnesses in Korma told journalists on Sunday of the 49 people killed, nine were hanged and various parts of the town were looted and burned.
One businessman said the militia began attacking the town, 95km northeast of Kebkabiya and 900km southwest of Khartoum, early on Thursday morning.
"One tree had three people hanging from it, and the 40 others were shot in the town centre," he said.
"They burnt two neighbourhoods … which had mainly African tribes living in them. They also burnt four surrounding villages."
The Sudanese government declined to comment, other than to say it considered all militia fighters as outlaws.
There are two rebel groups in revolt against the government in Darfur, both founded in February 2003.
They accuse the government of neglecting the region and arming local Janjawid militia who loot and burn Darfur villages.
In a separate incident, rebels from the Sudan Liberation Movement (SLM) said they had killed about 100 Janjawid fighters who had attacked a rebel garrison on Saturday.
"One tree had three people hanging from it, and the 40 others were shot in the town centre"
Korma resident describing Janjawid executions
SLM spokesman Muhammad Mursal also said the rebels had heard reports of the killings in Korma.
Minister: No Rwanda comparisons
Following some sharp UN criticism concerning the Darfur issues, Sudan will present an official complaint over statements by the world body's humanitarian coordinator.
The UN's Mukesh Kapila said the situation in Darfur was reminiscent of the Rwandan genocide.
But State Minister for Foreign Affairs Najib al-Khair Abd Al-Wahab said his government "wishes to know whether these statements are an expression of the UN's position towards the situation in Sudan or whether it is the private opinion of the resident humanitarian coordinator."
The UN has warned of a humanitarian crisis in Darfur and estimates one million people have been affected by the fighting with more than 100,000 refugees fleeing over the border to Chad.