The prosecutor in Turkey's largest city, Istanbul, has asked for the infamous mayor, Ekrem Imamoglu, to be sentenced to prison terms ranging from 828 to 2,352 years on 142 corruption charges.

Imamoglu, considered a key political rival of President Tayyip Erdogan, has been in prison since March last year on corruption charges.

The Istanbul mayor and the opposition Republican People's Party (CHP) have argued that they have done nothing wrong; accusing the president and his allies of acting in response to Erdogan's declining approval ratings.

But the city's chief prosecutor has indicted 401 people, not just Imamoglu, for "forming and leading" a corrupt criminal group along with the mayor.

After an eight-month investigation, prosecutor Akin Gurlek said the 105 suspects in custody formed a large criminal organization involved in bribery and money laundering.

Imamoglu, who was elected as the CHP party's candidate in the 2028 presidential election, faces 12 charges of bribery, seven of money laundering, and an additional seven of fraud against government and public institutions.