UNITED NATIONS (Reuters) - Exiled South Sudanese opposition figure Riek Machar declined to renounce violence or declare a unilateral ceasefire and instead demanded new peace talks outside the war-torn country, an international mediator told the United Nations on Thursday.

FILE PHOTO: South Sudan's rebel leader Riek Machar addresses a news conference in Addis Ababa, Ethiopia, October 18, 2015. REUTERS/Tiksa Negeri/File Photo

South Sudan descended into civil war in 2013 after President Salva Kiir fired Machar as his deputy, unleashing a conflict that has spawned armed factions often following ethnic lines.

Former Botswana President Festus Mogae told the U.N. Security Council that he visited Machar, who fled to Democratic Republic of Congo a year ago after fierce fighting in South Sudan. He is now being held in South Africa to stop him stirring up trouble, diplomatic and political sources told Reuters in December.

Mogae chairs the Joint Monitoring and Evaluation Commission, which was set up to monitor a failed 2015 truce and peace deal implementation. South Sudan has since launched its own national dialogue, while fighting has continued across the country.

“The message I conveyed to Dr Riek Machar was to renounce violence, declare a unilateral ceasefire and participate in the national dialogue. He declined to do so,” Mogae said. “He demanded a new political process by the region outside South Sudan.”

The United Nations has warned of a possible genocide as millions have fled their homes, the oil-producing economy is in a tail-spin, crop harvests are devastated because of the worst drought in years and millions face famine.

U.N. sanctions monitors reported to the Security Council earlier this year that South Sudan’s government is mainly to blame for famine in parts of the country, yet Kiir is still boosting his forces using millions of dollars from oil sales.

In December, the Security Council failed to adopt a U.S.-drafted resolution to impose an arms embargo and further sanctions on South Sudan despite warnings by U.N. officials of a possible genocide. The 15-member council remains split on how to try to bring an end to the conflict in South Sudan.

“I appeal to (East Africa regional bloc) IGAD, the African Union, the United Nations and our international partners to adopt one voice in our engagement with the leaders of South Sudan,” Mogae said.

He added that there was a “need for the regional leaders to align their messages and actions to prevent the situation in South Sudan from further deterioration.”

Rather than speaking with one voice, regional leaders have largely worked on South Sudan on a bilateral basis.