The army on Thursday warned of a possible confrontation between its troops and RSF fighters.
The Rapid Support Forces evolved from militias that fought in the early 2000s conflict in Darfur.
The FFC said it had held meetings last week with military leaders but "results were reached that had not been executed."
Khartoum
Sudan's main pro-democracy coalition have said that loyalists of former strongman Omar al-Bashir, who was ousted in a coup in 2019, are fuelling a rift between the armed forces and a powerful paramilitary group that has jeopardised a transition to civilian government.
The army on Thursday warned of a possible confrontation between its troops and fighters of the Rapid Support Forces (RSF), bringing long-bubbling disagreements to the surface.
A flurry of mediation offers quickly emerged, with local and international actors meeting army leader General Abdel Fattah al-Burhan and RSF head General Mohamed Hamdan Dagalo, who have served as Sudan's head of state and deputy head of state since they took part in the coup that ousted the Islamist Bashir.
"The ongoing events are the plan of loyalists of the former regime, aiming to destroy the political process," the Forces of Freedom and Change (FFC), a coalition of pro-democracy parties, said in a statement.
Power-sharing agreement
The FFC had been in a power-sharing agreement with the military following Bashir's overthrow until another coup in 2021, when the army and RSF ousted civilian leaders and took control.
The Rapid Support Forces evolved from militias that fought in the early 2000s conflict in Darfur into a complex paramilitary group with considerable funds operating under its own chain of command.
Disagreements between the army and the RSF over the reform and integration of their forces have delayed the final signing of a political deal that would restore civilian government.
The FFC said it had held meetings last week with military leaders but "results were reached that had not been executed." They were still in communication, it said.
Purge Bashir loyalists
Its leaders have said that a major aim of a new civilian government would be to purge the civil service of Bashir loyalists, who have resurfaced since the October 2021 coup.
Under Bashir's three-decade rule, those with loyalties to his National Congress Party (NCP) were favoured for positions in the government and military.
A leader of the now-outlawed NCP told Reuters this week the group was intensifying its action against the deal, which envisages elections in two years’ time.
‘Create discord’
NCP elements "aim to create discord between the armed forces and RSF and beat the drums of war" in order to regain power, a separate statement by civilian parties to the pending deal said on Thursday.
A desire to limit the spread of political Islam is seen by analysts as a driver behind foreign support for the deal, which has been mediated by Western and Gulf powers, as well as the United Nations and African Union.
"Sudan's military leaders must deescalate tensions, and stakeholders should engage constructively to resolve outstanding issues and reach a political agreement," US Assistant Secretary of State Molly Phee said in a statement.