Sudan's army suspended talks with the paramilitary Rapid Support Forces (RSF) on Wednesday, according to reports citing a government official.
Talks between Sudan's warring factions have been ongoing since early May and have produced two short-term cease-fire deals.
What has happened so far in the talks?
The army and the RSF had agreed to extend a previous truce by five days just before it was due to expire late on Monday.
The brokers of the cease-fire, Saudi Arabia and the United States, say it has been violated by both factions.
An anonymous Sudanese official told the Agence France-Presse (AFP) news agency that the army made the decision "because the rebels have never implemented a single one of the provisions of a short-term ceasefire which required their withdrawal from hospitals and residential buildings"
The official accused the RSF of having "repeatedly violated the truce."
Fighting had already been reported on Tuesday both in Khartoum's metropolitan area and in the western region of Darfur.
"The army is ready to fight until victory," army chief Abdel-Fattah Burhan declared while speaking in Khartoum on Tuesday.
The RSF accused the army of violating the truce, saying the paramilitaries would "exercise the right to defend themselves."
Sudan crisis raging since mid-April
More than 1,800 people have been killed in the conflict in Sudan since April 2015, according to the Armed Conflict Location and Event Data Project.
The United Nations says that over a million people have been internally displaced and nearly 350,000 have fled to other countries.Neighboring Egypt houses the largest group of Sudanese refugees, numbering over 170,000, and at least 60,000 have fled to Chad.
According to UN figures, around 25 million people in Sudan are in need of aid and protection, with entire districts of Khartoum being without running water and receiving only a couple of hours of electricity per week.