At least 33 people were killed and more than 100 injured in a twin bomb attack in Syria's border town Hassakeh late on Friday (20 March).
A suicide bomber set off an explosion at a new year's eve celebration observed by the Kurds to mark the start of spring and the first day of the Persian calendar.
The second blast was at another location where a similar gathering was celebrating, according to the Kurdish media.
Among those killed were children and 20 people are in critical condition, according to the Britain-based Syrian Observatory for Human Rights (SOHR).
No group has so far claimed responsibility for the terror attack but SOHR director Abdel Rahman suspects the hand of Islamic State militants.
"IS has faced setbacks recently in the provinces of Aleppo and Raqqa and in Hassakeh in confrontations with Kurds on the one hand and regime forces on the other, and are now trying to score military points, even limited ones, to offset their losses," Rahman said.
DPA news agency quoted local media to report that the first bombing targeted an office of the Kurdish Democratic group TEV-DEM and the second the office of the Kurdistan Democratic Party of Syria (PDKS).
The city lies in Syria's far northeastern corner, less than 100 km from the Turkish border.
In the continuing conflict since months, Kurdish fighters had last week succeeded in cutting IS off from an important supply route from Syria to Iraq.
Earlier in January, Kurdish fighters had driven the militants from the Syrian-Turkish border town of Kobane following days of fierce combat.