A court annulled the Istanbul provincial congress of Turkey's main opposition party on Tuesday, citing alleged procedural irregularities in a decision critics view as an escalating campaign to weaken the party.
The ruling against the Republican People's Party (CHP), led to the dismissal of Istanbul chair Özgür Çelik and other provincial administrators.
An interim committee was appointed to oversee the party's Istanbul branch.
The decision followed a legal challenge seeking to nullify the CHP's Istanbul congress on 8 October, claiming procedural violations.
It comes just weeks before a separate court in Ankara is expected to rule on a similar case targeting the CHP's main congress in 2023, which elected Özgür Özel as party leader.
A ruling against the CHP in that case could potentially reinstate its former leader, Kemal Kılıçdaroğlu, a figure whose tenure drew widespread criticism.
The court's ruling coincides with an escalating crackdown on municipalities controlled by the CHP, which resulted in a series of arrests beginning with Istanbul Mayor Ekrem İmamoğlu in March.
A prominent opposition figure, İmamoğlu is widely seen as the leading challenger to President Recep Tayyip Erdoğan’s two-decade rule.
The arrests have been made over allegations of corruption, which the CHP strongly denies.
İmamoğlu's jailing led to the largest protests in Turkey in more than a decade, with demonstrators denouncing a democratic backsliding under Erdoğan.
Critics argue the legal actions are politically motivated and designed to weaken the CHP’s rising influence.
Erdoğan's government insists that the judiciary operates independently and denies any political interference.
"This decision is a blatant blow to our democracy," Ali Mahir Başarır, a top CHP legislator, said in an X post following Tuesday's ruling.
"We will continue our legal and political struggle against those who attempt to usurp our will through judicial means."
Özel said the CHP would appeal the ruling.
Turkey's main stock index, the BIST100, dropped by more than 5% following the decision, before recovering some ground to close 3.57% down at 10,877 points.
Since 2019, Istanbul and several other major cities have shifted to CHP control, with the opposition further expanding its reach in last year's municipal elections.
