Analysts regard security sector reform as crucial to Sudan's chances of evolving into a democracy.
Talks in Khartoum this week were meant to provide guidance on how and when the RSF will be integrated.
While the army prefers a two-year timeline for integration, international facilitators have suggested five years.
A more formal constitutional declaration is meant to be signed on April 6.
Khartoum
Talks in Sudan aimed at reaching a final agreement to name a civilian government next month and launch a new transition towards elections have hit a roadblock over the thorny issue of restructuring the military, political and military sources said.
Disagreements surfaced this week over the timeline for integrating the powerful paramilitary Rapid Support Forces (RSF) into the military, a move called for in a framework deal for the new transition signed in December.
Integrating the RSF and placing the military under civilian authority are core demands of a protest movement that helped topple long-ruling autocrat Omar al-Bashir four years ago.
Crucial for democracy
Analysts regard security sector reform as crucial to Sudan's chances of evolving into a democracy.
Talks in Khartoum this week were meant to provide guidance on how and when the RSF will be integrated, but concluded late on Wednesday without issuing recommendations.
Army, police and intelligence withdrew from the talks in protest against the lack of any timetable for integration, two political sources and one military source told Reuters. Photos of the conference's closing session showed their seats empty.
While the army prefers a two-year timeline for integration, international facilitators have suggested five years, the sources said, while the RSF proposed 10 years.
Committed to talks
In statements on Thursday, both forces said they were committed to the talks and awaiting the results of a technical committee discussing details of integration.
The army and the RSF staged a coup in October 2021, ending a previous transition towards elections that had been launched after Bashir's ouster.
The new transition is meant to turn the page on the takeover, though negotiations ahead of an expected signature of a final accord on Saturday had already fuelled tensions that led both the army and the RSF to deploy forces in the capital.
A more formal constitutional declaration is meant to be signed on April 6, with a civilian government due to be named on April 11.