"We are living a very important moment in the Muslim calendar. I think this is the right moment for a ceasefire to hold," Guterres told reporters, adding: "We have been in contact with the parties, we believe it is possible."

The pause would "allow civilians trapped in conflict zones to escape and to seek medical treatment, food and other essential supplies," Guterres added.

More than 300 people have been killed since the fighting erupted Saturday between forces loyal to Sudan's army chief Abdel Fattah al-Burhan and his deputy, Mohamed Hamdan Daglo, who commands the paramilitary Rapid Support Forces (RSF).

The Eid ceasefire "must be the first step in providing respite from the fighting and paving the way for a permanent ceasefire," Guterres said.

"This ceasefire is absolutely crucial at the present moment," he added.

Some of the fiercest battles have taken place in the capital Khartoum, a city home to five million people, most of whom have been cloistered in their homes without electricity, food and water.

"The cessation of hostilities must be followed by serious dialogue allowing for the successful transition, starting with the appointment of a civilian government," Guterres said.