Syrian Kurdish forces and militias loyal to President Bashar al-Assad on Tuesday reached a ceasefire deal after more than a week of heavy clashes in al-Hassakeh that claimed dozens of lives.
The deal lets the Kurds keep positions gained in the fighting around the city in northern Syria and comes following days of negotiations between the sides brokered by Russia at its airbase in western Syria, according to officials.
Moscow is a key foreign backer of Syrian President Bashar al-Assad but at times also has courted the Kurds.
Heavy clashes in the city over the last week included Syrian government airstrikes against Kurdish positions for the first time in the history of the civil war, earning it a sharp warning from Washington.
The United Nations said on Tuesday that it was "extremely concerned" that recent fighting has displaced 65,000 people from al-Hassakeh to suburban neighbourhoods and surrounding villages.
"Given the scale and pace of displacement, not all needs can be met yet," said Stephane Dujarric, spokesman for UN Secretary General Ban Ki-moon, urging unhindered access to those in need.
Firat, a pro-Kurdish news agency, said the ceasefire was the result of an intervention of local tribal leaders and "some countries," without specifying.
The Kurdish forces in northern Syria have been the main ally on the ground of the United States in its war against the Islamic State extremist group. The Kurds seized Minbij city from the group this month and continue to advance.
According to a Syrian government source familiar with the negotiations, the Kurds had asked for Damascus to recognize areas in northern Syria where they have declared autonomous zones, but this was rejected.
The Syrian opposition and the government are both opposed to Kurdish autonomy, fearing a division of the country.
Kurds, a minority group in the mostly Arab nation, have long complained of systemic discrimination in Syria and are demanding a more federalized state, along the lines of their own autonomous zones, as part of the solution to the civil war.