They said 350 militiamen torched all but two buildings in Khor Abeche, 75km (47 miles) from Nyala on Thursday.
The organisations named Nasir al-Tijani as the militia leader and demanded action from Sudan’s government.
A two-year conflict between Sudanese pro-government Arab militias and black African rebels has left at least 180,000 people dead in Darfur.