ISTANBUL, Sept. 2 (Xinhua) -- A Turkish court on Tuesday annulled the main opposition Republican People's Party (CHP) Istanbul provincial congress held in 2023 and ousted Provincial Chairman Ozgur Celik and his administration over irregularities.

The Istanbul Chief Public Prosecutor's Office stated that the decision to suspend the Istanbul provincial chairman, provincial executive board members, and provincial disciplinary board members is a precautionary measure issued in response to a lawsuit filed by a group of CHP delegates.

In a brief message on the social media platform X, Celik said he was heading to the Istanbul Provincial Chairmanship to oversee and manage the process. "The decision is an attempt to block our march toward power," he added.

Celik, supported by Istanbul's former mayor Ekrem Imamoglu, defeated his rival in the 2023 election, and an investigation was subsequently launched against him over allegations of election fraud.

The state-run Anadolu Agency reported that the 2023 congress was deemed invalid due to irregularities. Investigations by the Istanbul Chief Public Prosecutor's Office and leaked audio recordings suggested that delegates' votes were influenced by money, gifts, job promises, and other material benefits.

A temporary trustee committee, headed by former provincial chairman Gursel Tekin, has been appointed to the Provincial Chairmanship.

Following the decision, the benchmark BIST-100 index on Borsa Istanbul tumbled by over 5 percent, while the banking index fell by 7.5 percent.

The ruling came amid increased scrutiny of the country's main opposition, during which over a dozen mayors -- including Imamoglu, a key rival of President Recep Tayyip Erdogan -- have been taken into custody. ■