UN Secretary-General Antonio Guterres on Friday called on Sudan's military rulers and protest groups to go back to the negotiating table and quickly reach a deal on handing over power to a civilian-led government.
Guterres said in a statement that the sides must "conclude the negotiations over the transfer of power to a civilian-led transitional authority as soon as possible."
Negotiations between protesters and the military council have broken down over whether a planned transitional body would be headed by a civilian or a military figure.
The deadlock has raised fears that the military will seek to tighten its grip on power, crushing hopes of a democratic process in Sudan.
On Friday, hundreds of people rallied in support of Sudan's military rulers in Khartoum.
The military council has ruled the country since the ouster of president Omar al-Bashir on April 11, after months of protests against his authoritarian rule.
Guterres called for the "utmost restraint" and stressed the importance of upholding human rights, including the right to freedom of assembly and of expression.
Sudanese authorities on Thursday shut down the Khartoum office of Qatari-owned Al Jazeera television and banned its journalists from reporting in the country.
Sudan's generals, backed by key Arab powers, have resisted calls from African and Western governments to hand over the reins of power.
The head of the ruling military council, General Abdel Fattah al-Burhan, paid a visit to Saudi Arabia this week following talks in Egypt last week.
On May 14, the protest leaders and the military reached a breakthrough by agreeing on a three-year transition period for transferring power to a civilian administration.
They also agreed that parliament be composed of 300 members for the transition, with around two-thirds from the protest alliance and the rest drawn from other political groups.
But negotiations were suspended the following day by the military, which demanded that demonstrators remove roadblocks following clashes in which five people were killed.
Talks resumed on May 19 but broke down the following day over disagreement on whether the military or a civilian should lead the transitional authority.
The UN chief has called for a transition in Sudan that meets the "democratic aspiration" of the Sudanese people.