Syrian rebels clashed with Kurdish militia in the northern city of Aleppo, leaving 30 dead and around 200 captured, a watchdog said on Saturday, sparking fears of a new front in an already fractured country. The fighting between armed rebels and members of the Kurdish Democratic Union Party (PYD), the Syrian branch of the Kurdistan Workers' Party (PKK), erupted on Friday in the majority Kurdish neighbourhood of Ashrafiyeh, it said. "There were 30 people -- Arabs and Kurds -- killed in the fighting, including 22 combatants from both sides," the Syrian Observatory for Human Rights said in a statement, adding that Ashrafiyeh was still under PYD militia control. Some 200 people were captured, all but 20 of them by the rebels, the Observatory said. Residents said some 200 rebels had moved in to the area on Thursday, announcing they had come to spend the Muslim holidays of Eid al-Adha, starting the next day, in the neighbourhood. Before they moved in, the Kurdish area of Aleppo had been relatively free of the violence that has plagued the city since fighting between President Bashar al-Assad's forces and armed rebels broke out there on July 20. Some 15 percent of Syria's population of 23 million are Kurds. The minority has largely remained neutral during the country's civil war, which has sown divisions among its patchwork of ethnic and religious groups. Rami Abdel Rahman, director of the Britain-based Observatory, said if Kurdish militias were to join the fighting, the results could be devastating. "There are 100,000 Kurds in Aleppo province ready to fight if need be," he said. "If Arab-Kurdish fighting really kicks off, then you can forget about the revolt and Assad stays." Friday's fighting was the fiercest clash between Kurds and rebels since the March 2011 start of Syria's conflict. Strategically important, Ashrafiyeh sits in Aleppo's heights and on a route between the city's north and centre. Over the summer, the army withdrew from majority Kurdish areas, including Ashrafiyeh and several towns on the Turkish border, leaving Kurds with some degree of autonomy. Rebel fighters are only allowed to enter these areas unarmed and in civilian clothing. A PYD statement published after the fighting blamed both Assad's regime and the rebel Free Syrian Army (FSA) for violence against Kurds. "We have chosen to remain neutral, and we will not take sides in a war that will only bring suffering and destruction to our country," the statement said. For two days before Friday's clash, the army shelled Ashrafiyeh, the PYD said. On Friday, the FSA stormed a road that cuts through Ashrafiyeh and the nearby Sheikh Maksud district, it added. "They started to shoot at crowds gathered at the (militia) checkpoints," it said. "They were protesting, calling on the armed groups to leave residential areas." A rebel group described Friday's violence as the result of a misunderstanding and blamed it on Assad's regime. "Our Kurdish brothers are comrades in our nation," the Free Syrians Brigade said in a statement. "The problem... was the result of a misunderstanding that was created by a regime plot." Massud Akko, a prominent Kurdish activist and journalist from Syria, said he feared Assad would use Friday's violence to stir up conflict between the rebels and Kurdish militia. "While I am opposed to the Free Syrian Army's entry into safe areas, Assad's regime is looking for ways to create conflict among Syrians," he said. The conflict, which has pitted the regime against rebel fighters since a revolt against Assad morphed into an armed insurgency, has left at least 35,000 people dead, according to the Observatory. The PKK, listed as a terrorist group by the West, took up arms in the Kurdish-majority southeast of Turkey in 1984.