The government of the Democratic Republic of Congo and the M23 movement have failed to reach a peace deal in Doha on Monday, missing the deadline they had set in earlier meetings.
This raises fears that the two parties might reverse the progress made to end hostilities.
Fighting in the eastern DRC escalated in January, when the Rwanda-backed M23 rebels seized large parts of the area, including the regional capital of Goma.
The rebels and the Congolese government signed a declaration of principles in July under a Qatari mediation.
With this agreement, the two parties committed to a ceasefire. It was also supposed to pave the way for further peace negotiations, with the goal of reaching a deal by 18 August.
A Qatari official said on Sunday that a draft agreement to end fighting had been shared with the Congolese government and the rebels.
But in a statement on Sunday, the M23 movement said peace talks would not resume, unless all terms of the declaration of principles were fully implemented. This includes the release of prisoners.