A security force action in Qamishli on Sunday to disperse Kurdish demonstrators angry at the abduction and murder of a leading Muslim cleric, Shaikh Mohammed Mashuk Khaznawi, turned into Arab-Kurdish clashes, Kurdish Progressive Democrat Party leader Aziz Daud said.
Yakiti party leader Hassan Saleh said the situation in Qamishli remained tense after several demonstrators were wounded and dozens arrested.
Daud said 50 Kurdish-owned shops had been ransacked by militiamen during the clashes.
Qamishli has been on edge since deadly clashes in March last year pitted Kurdish protestors against security forces and Arab tribesmen.
The Syrian authorities said that 25 people were killed. Kurdish sources put the death toll as high as 40.
Kidnap and killing
The latest violence followed the kidnapping and murder of popular local cleric Khaznawi.
The Syrian authorities said two people had already been detained in what it promised would be a full investigation.
Syrian Kurds find themselves
facing social disadvantages
But the fact that the death was first announced by underground Kurdish sources and only later confirmed by the government sparked widespread scepticism among Syria's Kurdish minority.
Syria's 1.5 million Kurds make up about 9% of the population and are mainly concentrated in the north.
About 200,000 have been denied Syrian citizenship, making it difficult for them to find work in the state-controlled economy.
Meanwhile in Austria trespassers broke into the Syrian embassy in Vienna and replaced the national flag with a Kurdish one, the police said on Monday.
Embassy staff arrived at work on Monday morning to find that a wooden door had been forced open and the red, white and green Kurdish flag was flying from a balcony, a spokeswoman for the Vienna police said.
"Nothing was stolen and we do not know who did this, or how many people were involved," she said.
Aljazeera also reported that the Syrian Organisation for Human Rights announced that Syrian security forces had arrested an activist at Civil Society Committees, Riyadh Dharrar, in the eastern city of Dair al-Zur.