Sudan announced Wednesday a "permanent ceasefire" in the country's war zones even as a key rebel group threatened to pull out of peace talks, accusing government forces of bombing its territory.

Juba has been hosting talks between new Prime Minister Abdalla Hamdok's government and delegates from two umbrella groups of rebels who fought now ousted president Omar al-Bashir's forces in Darfur, Blue Nile and South Kordofan states.

The talks were launched on Monday, but the rebel Sudan People's Liberation Movement North (SPLM-N) said it would pull out unless the government withdrew from an area in the Nuba mountains.

The group said that for the past 10 days government forces had kept up attacks on its territory despite an unofficial ceasefire.

Late on Wednesday, the chief of Sudan's ruling sovereign council, General Abdel Fattah al-Burhan, announced a permanent ceasefire in the three conflict zones.

"General Abdel Fattah al-Burhan has announced a permanent ceasefire to show that the government is committed to peace," the sovereign council said in a statement.

"The ceasefire is valid from the signing of this declaration."

An unofficial ceasefire had been in place since Bashir was ousted by the army in April in a palace coup following nationwide protests against his decades-old rule.

A joint civilian-military sovereign council is now ruling Sudan and is tasked with overseeing the country's transition to civilian rule as demanded by protesters.

A new transitional government is in place to carry out the daily affairs of the country, and has been leading the peace talks in South Sudan's capital with the rebel groups.

Bloodshed in the three states has left hundreds of thousands of people dead and millions displaced, in turn severely impacting the northeast African country's economy.