Kurdish-led forces were sending reinforcements to eastern Syria's Deir el-Zour province on Monday amid days of clashes with Arab fighters loyal to a detained local official, an AFP correspondent said.
Fighting erupted after the U.S.-backed Syrian Democratic Forces (SDF) detained Ahmad al-Khabil, head of the Deir el-Zour Military Council, on August 27.
The violence in several towns and villages in Kurdish-controlled areas of Deir el-Zour province has killed 71 people, mostly fighters but also nine civilians.
SDF spokesman Farhad Shami told AFP his forces were trying to "settle" the situation in Dhiban, the last town where fighters loyal to Khabil were concentrated.
"We urged civilians to leave," Shami said, adding that the situation was heading towards "a settlement and the end of tensions" after other villages where clashes took place were searched in recent days.
The AFP correspondent saw Kurdish and Arab fighters from the SDF heading on trucks towards Dhiban.
Arab-majority Deir el-Zour province, a resource-rich region which borders Iraq, is bisected by the Euphrates river and is home to dozens of local tribal communities, some of whose fighters joined the SDF in its battle against the Islamic State jihadist group (IS).
Control of the province is split between the SDF to the east of the Euphrates, and Iran-backed Syrian government forces and their proxies to the west.
The Syrian Observatory for Human Rights, a war monitor, said dozens of fighters who follow a sheikh from a prominent tribe were still positioned in Dhiban, adding that residents were fleeing the area.
The tribes are divided in their loyalties, added the Britain-based Observatory, which has a vast network of sources inside Syria.
The SDF has denied any dispute with Arab tribes in the region, saying the clashes have mostly involved "elements of the regime and some beneficiaries" of Khabil, whom they accuse of drug trafficking and communicating with the Syrian government.
It has urged local residents "not to be drawn into the strife.
A semi-autonomous Kurdish administration controls areas in north and northeast Syria through local civilian and military councils in an effort to stave off Arab discontent.
In northern Syria on Monday, Turkey-backed fighters who said they were from Arab tribes attacked SDF positions in support of the local fighters in Deir el-Zour.
With U.S. backing, the SDF spearheaded the offensive that defeated IS's self-declared caliphate in Syria in 2019.
The U.S. Embassy in Syria, which is based outside the country, said Sunday that two senior officials had met with the SDF, Kurdish authorities and tribal leaders from Deir el-Zour, urging de-escalation "as soon as possible."