A Turkish prosecutor has demanded a prison sentence of more than 2000 years for jailed Istanbul mayor Ekrem Imamoglu for allegedly leading a vast corruption network that cost the state billions of lira, according to an indictment seen by Reuters.

Imamoglu, who is President Tayyip Erdogan's main political rival, has previously denied all the accusations against him and said they are politically motivated.

Istanbul Chief Prosecutor Akin Gurlek announced the indictment at a press conference on Tuesday, saying it names 402 suspects, including Imamoglu, and accuses them of forming a criminal organisation, bribery, fraud and bid-rigging.

Gurlek said the network caused 160 billion lira ($A5.8 billion) in losses to the Turkish state over a 10-year period.

The more than 4000-page indictment inc

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