At least 270 people have been killed since clashes between the army and the Rapid Support Forces broke out, the World Health Organization said, citing Sudan’s health ministry.
Another 2,600 people have also been injured, it added.
The Sudan Doctors’ Union has said that at least 30 people have been killed since an agreed ceasefire was supposed to take effect at 6pm (16:00 GMT) on Tuesday.
Meanwhile the RSF says it is committed to a 24-hour ceasefire starting at 6pm local time (16:00 GMT).
“We confirm our full commitment to a complete ceasefire, and we hope the other party will abide by the ceasefire according to the announced time,” it said in a statement.
There was no immediate comment by the Sudanese army.
The two sides on Tuesday had announced their commitment to a 24-hour ceasefire but fighting continued in parts of the country.