The Kurdish National Council -- the main rival coalition of the dominant Democratic Union Party (PYD) and a member of the Syrian opposition National Coalition -- was among several groups whose offices were shut.

Hakam Khelo, who co-heads the legislative council of the autonomous Kurdish authorities in northeastern Hasakeh province, told AFP the closures were in line with a three-year-old law.

"We're implementing the political party licensing law which was issued by the autonomous administration three years ago. Parties that have not licensed their offices will be legally closed," Khelo said.

Taking advantage of the Syrian army's withdrawal from swathes of northern territory, Kurdish authorities declared three "autonomous" cantons there in 2013.

The following year, they issued a decree requiring political parties operating in the cantons to be licensed, but it remained unclear why it was not implemented until this year.

KNC member Fuad Aliko told AFP in Beirut the closure were tantamount to "harassment of KNC activists and leading members, after our offices were attacked and officials were arrested".

"This behaviour is part of a political purge of any opposition," Aliko said.

Mohsen Taher, another KNC member, told AFP: "What the PYD did recently with shutting offices... does not serve the Kurds or the Kurdish position at this time".

"These actions will not benefit them -- on the contrary, they will contribute to destabilising the region and exacerbating public fissures," he said.

Kurdish authorities also closed the offices of the Assyrian Democratic Organisation, one of the oldest groups representing the Christian sect in Syria.

The Assyrian Observatory for Human Rights reported the ADO's closure, calling it "arbitrary".

Khelo said the KNC and other groups had received "multiple warnings... but they did not present the necessary paperwork to be licensed".

The PYD and its powerful military arm, the Kurdish People's Protection Units (YPG), dominate much of the political scene in northern Syria.

The YPG is the primary component of a US-backed alliance of fighters that has captured swathes of territory from the Islamic State jihadist group.

The PYD and other groups declared a "federal" system across the three Kurdish cantons last year, a declaration lambasted by Syria's regime, the opposition, and groups like the KNC.