The Labor and Social Security Ministry on Monday launched a sequestration process for six city administrations run by Türkiye’s main opposition party, the Republican People's Party (CHP).

The deposit and corporate accounts of the metropolitan municipalities of Istanbul, Ankara, western Izmir, southern Adana and Mersin, and Istanbul’s Şişli district, have been blocked due to unpaid debts to the Social Security Institution (SGK), the ministry said in a statement.

The said administrations have the highest debts to the SGK, according to the ministry.

Labor and Social Security Minister Vedat Işıkhan last month warned authorities would begin a confiscation process if the municipalities continued not taking action to address their debts despite persistent calls.

Although some municipalities run by the ruling Justice and Development Party (AK Party) also have outstanding debts, opposition-run municipalities pull the lead, according to Işıkhan.

A total of 411 CHP municipalities countrywide are also facing legal action over unpaid debts to the SGK running into the billions.

Official figures released before the March 31 local elections showed municipal companies had accrued TL 96 million in premium debt rather than the city itself, but the number has increased to TL 150 billion.

CHP-run municipalities owe 67.5% of the debt while AK Party municipalities own 25% of the SGK premium debt.

CHP’s Istanbul and Ankara municipalities are also currently under probe for "unlawful" spending on celebratory events.