The heads of Sudan's rival military factions have given competing addresses to the United Nations, one from the podium at UN headquarters in New York and the other in a rare video recording from an undisclosed location.

Army leader Abdel Fattah al Burhan, speaking at the United Nations on Thursday, called on the international community to designate the paramilitary Rapid Support Forces [RSF] as a terrorist organisation and to counter its sponsors outside Sudan's borders.

"Our country's legitimate institutions will not tolerate any form of violence or the humiliation of our people. The regional and international interventions in support of the RSF have become evident, and this represents the initial spark that could ignite turmoil within the region and beyond," he said.

RSF leader Mohamed Hamdan Dagalo, known as Hemetti, said in a video message that his forces were fully prepared for a ceasefire and comprehensive political talks to end the conflict.

Both sides blamed the other for starting the war that erupted in mid-April in Khartoum and has spread to other parts of the country, including the western region of Darfur, displacing more than 5 million people and threatening to destabilise the region.

Most of Hemetti's recent communications have been audio messages, and his whereabouts have been a source of speculation.

In the video released on Thursday shortly before Burhan spoke, he appeared in military uniform, seated behind a desk with a Sudanese national flag behind him as he read out his speech.

His location was not clear.

Conflict in Sudan

Previous assertions by the army and the RSF that they are seeking a solution to the conflict, as well as announcements of ceasefires by both sides, have failed to stop the bloodshed and the deepening of a humanitarian crisis in Sudan.

The war broke out over plans to formally integrate the RSF into the army as part of a political transition four years after the overthrow of former leader Omar al Bashir during an uprising.

Witnesses say the army has used heavy artillery and air strikes that have caused casualties in residential districts of Khartoum and other cities and that the RSF has inflicted widespread looting and sexual violence on residents and participated in ethnically targeted attacks in Darfur.

The fighting in Sudan has killed at least 7,500 people, according to the NGO Acled, and displaced some five million people, dealing a new, devastating blow to efforts to bring democracy to Sudan.