A plan by Ethiopia to give civilians the majority in a new Sudan transitional government has been flatly rejected by the ruling military council.
The junta accused the Ethiopian initiative - in which the military and the protest movement would have seven seats each and independent head - of attempting to impose a specific proposal on the parties.
"That is unacceptable because its violates the sovereignty of Sudan. Sudan is not accepting any external intervention that is trying to impose any kind of solutions without our opinions and consultations," Transitional Military Council (TMC) spokesman Shams Aldin Al-Kabashi said.
Yassir Al-Atta, a TMC member also said the Ethiopian initiative was different from that of the African Union and the two needed to be harmonised.
Details of the AU proposal have not come to light as it was understood all along that Ethiopian Prime Minister Abiy Ahmed had been picked by the AU to mediate in the crisis.
The rejection of the terms by TMC is a major setback in the reconciliation talks that are key to returning Sudan to civilian rule.
Analysts says that the initiative was headed for turbulent waters because of the way it was publicised by the protestant Alliance of Freedom and Change (AFC) gave it a partisan feel.
Ideally, a truce involving parties in negotiations should be announced by the mediator with the protagonists also signing on the dotted line.
On Saturday, Babikir Faisal, a member of the AFC, told reporters that the alliance had accepted the Ethiopian initiative.
"We have told the Ethiopian envoy that the FFC has accepted their initiative. We hope all the political rivals will accept it to move the talks forward on the formation of civilian rule in Sudan," Mr Faisal said.
TMC has now said it has repudiated previous agreements with the alliance on a legislative assembly and an administration which were to be dominated by civilians.
Instead, it threatened to form a unilateral civilian government without reference to the alliance that led protests since December culminating in the April ouster of President Omar al- Bashir by the military council.
The agreements reached in April allowed the alliance to exclusively form a council of ministers (a government) and to constitute two thirds of parliament.
They has also agreed on a three-year transition to civilian rule during which the constitution and other key state institutions would be looked into to empower democracy.
The composition and chairmanship of the Joint Transitional Council, however, has been contested since leading to the paramilitary Rapid Support Forces breaking up a sit-in at army headquarters where officially 61 people were killed.
The alliance which pulled out of the talks over the attack puts the death toll at more than 128 and has rejected participation in any face-to-face talks with the junta.
Neighbours are watching with anxiety as any escalations would have far-reaching consequences on security in the region as well as the worsening refugee problem.
South Sudan has been keen to mediate in the Sudan impasse despite having unresolved issues back at home over the peace agreement.
On Friday, a delegation led by President Salva Kiir's security advisor joined the Ethiopian team in building bridges.
Its key interest is protecting oil flows, Juba's main source of revenue, which go through pipelines in Sudan territory before reaching foreign markets.
Mr Kew said the military rulers and the alliance should end their hard-line positions to ensure the return of peace and stability in Khartoum.
"Yes, we are concerned of the situation and that is why we came here to Khartoum to tell the parties to embrace peace," Mr Kew said in Khartoum on Friday, June 21.
The Inter-governmental Authority on Development (Igad) had issued a day earlier calling for a peaceful political transition in Sudan.