Puoch Riek Deng, spokesman for the rebel delegation, charged the government had not ordered Ugandan troops withdrawn or released all detained political leaders, the Sudan Tribune reported Tuesday.
Deng said the delegation was not boycotting the negotiations but waiting for its demands from the first round of talks to be fulfilled.
The government of President Salva Kiir and opposition Sudan People's Liberation Movement forces led by former Vice President Riek Machar signed a cease-fire deal Jan. 23.
The government later released seven of 11 members of the SPLM party who had been detained after what Kiir called an attempted coup.
The SPLM wants the four party members still in detention to be released.
Despite the cease-fire agreement, fighting between government troops and rebels has continued, with each side blaming the other for violations.
Since the conflict began two months ago, an estimated 10,000 people have been killed and 700,000 forced from their homes. About 150,000 people have fled to other countries.