An emergency regional summit planned for Thursday in the capital of war-torn South Sudan has been cancelled, official media in Khartoum said.
The East African regional bloc IGAD has been mediating in talks in Ethiopia between troops loyal to President Salva Kiir and rebels allied to his sacked deputy, Riek Machar.
But those talks are deadlocked and IGAD, the seven-member Intergovernmental Authority on Development, had called the special summit for Thursday in South Sudan's capital Juba.
"The government received an urgent memo today from the IGAD secretary informing them that the emergency summit... has been cancelled", Sudan's official SUNA news agency quoted Abdul Mahmud Abdul Halim, a senior official in Khartoum's foreign ministry, as saying Tuesday.
The report gave no reason for the cancellation.
South Sudan's foreign ministry spokesman Mayen Makol said earlier that he hoped all seven IGAD heads of state would attend.
"The key agenda of course is the negotiations in Addis Ababa," Makol told AFP.
Sudan's President Omar al-Bashir was to lead his country's delegation to the summit, based on an invitation from Ethiopian Prime Minister Hailemariam Desalegn, IGAD's chairman, SUNA reported on Monday.
Thousands have been killed and half a million civilians forced to flee the fighting which began mid-December in South Sudan.
The South became independent from Khartoum in 2011 under an agreement that ended a 22-year civil war.