Flooding has left between 65,000 and 70,000 families homeless in the eastern Sudanese city of Kassala, and rising Nile waters were raising fears of further devastating floods.
Several local newspapers said the flooding was the worst in 70 years in Kassala, a city of half a million people where supplies of food and clean water are running out.
The average Sudanese family numbers about six people, meaning up to 420,000 in the city could be without shelter.
The Al-Anbaanewspaper said six people were killed in the floods in Kassala, about 450 km (280 miles) east of Khartoum.
Heavy rains have also been reported in several other parts of Sudan, including the capital Khartoum and other regions along the Nile river, but most flooding has been limited to Kassala.
In 2001, heavy flooding of the Nile and torrential rains in southern Sudan made thousands homeless. In 1988, dozens of people were killed and around two million lost their homes after the Nile burst its banks in Sudan, Africa's largest country.