There had been hopes of progress towards a peace deal that could end four years of fighting in the region that has claimed more than 200,000 lives.
But many rebel leaders stayed away from the conference in the Libyan coastal town of Sirte, dashing hopes that an agreement could be quickly reached.
'Road to peace'
The mediators played down the postponement of the conference, insisting that the preliminary low-level talks were a necessary build-up for full-fledged negotiations and other groups could join the process over coming weeks.
|"The train has left on the road to peace ... the question is |
how many passengers will come on"
"I refuse to state that the peace process is interrupted. The train has left on the road to peace ... the question is how many passengers will come on," Jan Eliasson, the UN mediator, said.
Mediators stated they would remain in Libya, but envoys from their teams could be sent to Darfur or elsewhere to press rebel leaders to attend.
The special envoy from China, which has considerable influence on Sudan's government, also said postponing would allow more constructive peace talks later.
"The adjournment is not a sign of failure. It's a preparation of other steps," Liu Guijin said.
Nafie Ali Nafie, the Sudanese government representative, earlier said negotiations should be adjourned only to allow "those who came here" to have more time to reach a common ground.
"To adjourn negotiations for those who didn't come is a wrong signal," he said.
In a joint statement, the six factions that attended the talks called on the mediators to set a timeframe for further negotiations with the rebel groups that are boycotting the peace talks to try to persuade them to take part.
"To reach a just and comprehensive peace ... we want no significant armed group to be sidelined," it said.
The government had opened the conference by announcing a unilateral ceasefire but many of the groups which boycotted the event were dismissive of it.
Dozens of ceasefires have been announced and then breached by Khartoum or the rebels since 2003, when ethnic African fighters rose up against the Arab-dominated central government, accusing it of discrimination.