A suicide bomber killed more than 20 people celebrating Kurdish Nevruz festival in Syria's north-eastern province al Hassakeh, Friday and dozens were wounded in another blast at a separate feast, a monitor said.
"More than 20 people were killed when a kamikaze bomber detonated his explosives at a gathering in Hasakeh on the eve of (Kurdish new year) Nevruz," Observatory director Rami Abdel Rahman said.
Dozens more were wounded but some are in critical condition and the death toll may rise, he added.
There was no immediate claim of responsibility for the attack, but Abdel Rahman said the suicide bomber could have been a member of the ISIS.
He said a second bomb exploded at another Nowruz celebration, wounding dozens of people.
Syrian state news agency SANA also reported a "terrorist" attack in the centre of Hasakeh that killed and wounded "many civilians" and damaged homes, shops and cars.
Hasakeh is a strategic province in northeastern Syria near its borders with Iraq and Turkey.
ISIS controls several parts of the province while fighters from the Kurdish People's Protection Units (YPG) hold the provincial capital, which is also called Hasakeh.
The YPG are sworn enemies of ISIS, which they expelled from the border town of Kobane in January after four months of fierce fighting with help from allied air strikes.
The overall commander of the Asayish, or Kurdish security forces, Joan Ibrahim, said "the crime that occurred today in Hasakeh will not pass without retribution", YPG said on one of its Facebook pages.
