HASAKA (Syria)/BEIRUT/AMMAN: Syrian Kurdish forces took near complete control of Hasaka city on Tuesday as a ceasefire ended a week of fighting with the government, consolidating the Kurds' grip on Syria's northeast as Turkey increased its efforts to check their influence.
The Kurdish YPG militia, a critical part of the US-backed campaign against IS, already controls swathes of northern Syria where Kurdish groups have established de facto autonomy since the start of the Syria war in 2011.
Their growing sway has alarmed Turkey, which is fighting an insurgency among its own Kurdish minority.
Syrian rebels backed by Turkey said they were in the final stages of preparing an assault from Turkish territory on the IS-held Syrian border town of Jarablus, aiming to preempt any YPG attempt to take it.
The battle over Hasaka marked the most violent confrontation between the YPG and Damascus in more than five years of civil war, with the Syrian air force used against the US-backed Kurdish forces for the first time last week.
On Tuesday Hasaka's remaining government officials were confined to a few buildings known as the security quarter, while the rest of the city was under Kurdish control.
The Kurds held around 70 per cent of Hasaka prior to the latest fighting.
"Even if they (pro-government militias) keep a symbolic presence, it is a big defeat for the regime in Hasaka," said Rami Abdulrahman, director of the Syrian Observatory for Human Rights, which reports on the war.
The terms of the ceasefire that came into effect at 2 p.m. (1100 GMT) on Tuesday included the withdrawal of the Syrian army and allied militia from Hasaka city, Kurdish officials said.
The YPG would hand over all seized areas to an affiliated Kurdish police force, the Asayish.
Government policemen would be left to secure the one remaining area under state control.
Details reported by state TV included a prisoner swap, handing over the wounded and bodies of the dead, and opening the roads to Syrian army positions inside and outside the city.
Reuters could not immediately obtain a full text of the agreement. One of the Kurdish officials said the deal was concluded on Monday evening "via international parties".
YPG-controlled areas of northern Syria include an uninterrupted 400 km (250 mile) stretch of the Syrian-Turkish border from the eastern frontier with Iraq to the Euphrates river, and a pocket of territory in northwestern Syria.
Turkey is currently focused on preventing the YPG or its allies building on recent advances against IS by capturing the town of Jarablus.
The US-backed Syria Democratic Forces alliance (SDF), including the YPG, captured the city of Manbij, just south of Jarablus, from IS earlier this month.
Turkey has been shelling IS positions in Jarablus as part of an effort to help allied Syrian rebels secure it.
Rebel sources say they have been mobilising in Turkey, ready to cross into Jarablus.
A Syrian rebel with one of the Turkey-backed groups said the fighters were waiting for the signal to enter Jarablus.
"The Turkish artillery has not stopped ... this is to create the right atmosphere to start the battle of liberating Jarablus," said the rebel, who declined to be identified.
A second rebel familiar with the preparations said around 1,500 fighters were now gathered at a location in Turkey to take part. "The plan is to take Jarablus and expand south ... so as to abort any attempt by the Kurds to move north ... and so that Kurds don't take more villages," he said.
The leader of the newly declared "Jarablus military council", set up with the aim of mounting its own campaign to seize Jarablus with SDF support, was assassinated on Monday, the Observatory said.
A Kurdish official said two "agents of Turkey" had been detained over the killing.