"The talks are not resuming today," South Sudan government spokesman Michael Makuei told AFP. A government official from host country Ethiopia confirmed the postponement.
Makuei said the second round would start tomorrow, but there was no immediate confirmation.
"We are informed that his excellency the prime minister of Ethiopia wants to attend the opening session. We are told that it is tomorrow afternoon," Makuei said.
The first round of talks last month resulted in the South Sudan government side and rebels led by former vice president Riek Machar signing a ceasefire agreement, but fighting has continued in the vast and impoverished country.