RSF leader General Mohamed Hamdan Dagalo, whose whereabouts since the war began in mid-April were previously unknown, landed in Ethiopia's capital Addis Ababa after meeting Ugandan President Yoweri Museveni at his country home on Wednesday.
Diplomatic efforts, including Saudi and US-led talks in Jeddah, have made little visible progress towards halting the conflict in Sudan.
The RSF has recently made military gains, taking control of Wad Madani, one of Sudan's major cities, and consolidating its grip on the western region of Darfur.
Ethiopian Prime Minister Abiy Ahmed said he had received Dagalo and his delegation "for a discussion on securing peace and stability in the Sudan," posting pictures of them seated around a restaurant table.
Ethiopian Deputy Prime Minister and Foreign Minister Demeke Mekonnen earlier met Dagalo, commonly known as Hemedti, at Ethiopia's Bole International Airport.
Hemedti posted pictures of his arrival and a meeting with Demeke on social media platform X.
"We discussed the need to bring a swift end to this war, the historical crisis in Sudan, and how to best alleviate the hardships of the Sudanese people," Hemedti said.
Earlier today I received Mohamed Hamdan Dagalo and his delegation for a discussion on securing peace and stability in the Sudan. — Abiy Ahmed Ali 🇪🇹 (@AbiyAhmedAli) pic.twitter.com/D7IDwFTHihDecember 28, 2023
Posts by Hemedti and Ethiopia's foreign ministry showed him disembarking from an aircraft belonging to Royal Jet, a United Arab Emirates airline, which flight records show had flown from Abu Dhabi to Uganda's Entebbe airport on Wednesday morning.
Reuters was not immediately able to verify if Dagalo had been on the aircraft's previous flight.
The UAE, which has strategic interests in the Horn of Africa and has pursued investments in Sudan including a Red Sea port, has been Hemedti's most important foreign ally since before the current conflict.
Last month, a top Sudanese general accused the UAE of backing the RSF's war effort, funnelling supplies through countries including Uganda.
The UAE said in response that it supported diplomatic dialogue and de-escalation in Sudan while Uganda said the accusations were false.
War between Sudan's regular army and the RSF broke out amid disputes about the future powers and status of the army and the RSF under a planned transition from military rule to a civilian democracy through free elections.
The conflict has devastated the capital Khartoum, forced more than seven million people to flee their homes and triggered waves of ethnic killings in Darfur.
Survivors have identified commanders from the RSF and allied Arab militias as playing a key role in directing the violence in Darfur.
Most of the commanders did not respond or could not be reached for comment.
The RSF has previously denied being behind the violence in Darfur, blaming it on tribal dynamics.
Earlier this month, east African regional body IGAD said it had secured an agreement for a meeting between Hemedti and army chief Abdel Fattah al-Burhan and a commitment to a ceasefire, but both sides distanced themselves from the assertion.
