Istanbul prosecutors have charged eight people with corruption and fraud and placed them in pre-trial detention as part of a sweeping graft probe that has shaken the Turkish political establishment, media reports said Friday.
The eight are the first to be formally arrested out of 52 people detained in a series of dawn raids on Tuesday. They are suspected of numerous offences including accepting and facilitating bribes for development projects and securing construction permits for protected areas in exchange for money.
The sons of three ministers and several top business leaders were among those caught up in the mass detentions.
The remaining detainees are expected to appear in court in Istanbul on Friday after being interrogated by police, according to local media. The Hurriyet daily said five had already been released though there was no official confirmation of this.
Several dozen senior police officers have been fired in the wake of the raids, including Istanbul police chief Huseyin Capkin, accused of "abusing their power".
A further 14 senior police officials were removed from their posts in Ankara on Friday, reports said.
Turkish Prime Minister Recep Tayyip Erdogan has described the high-profile corruption investigation as a "dirty operation" to smear his Islamic-leaning government ahead of elections next year.
The appointment of new Istanbul police chief Selami Altinok, who was a governor in a small province with no career in the police department, has been condemned by critics as an attempt to shut down the investigation.
Altinok further raised eyebrows when he landed in Istanbul on Thursday in the premier's private jet.
The graft probe has exposed bitter fault lines in Erdogan's traditional power base and prompted calls from opposition parties for the resignation of the entire government.
"In this country, everything is controlled by what comes out of a dictator's mouth... They want to drag the country into the darkness of 19th century," Kemal Kilicdaroglu, the leader of main opposition Republican People's Party (CHP) said Friday.
"Turkey needs clean politics and a clean society."
The European Union, which Turkey aspires to join, on Thursday urged Turkish authorities to investigate the graft allegations in an "impartial manner."
Among the suspects detained in the raids are the sons of Interior Minister Muammer Guler, Economy Minister Zafer Caglayan and Environment Minister Erdogan Bayraktar along with the chief executive of state-owned Halkbank, Suleyman Aslan, and construction tycoon Ali Agaoglu.
Erdogan's ruling Justice and Development Party (AKP) has vowed to root out corruption, a chronic problem in Turkey.
But some political observers have speculated that the raids stemmed from tensions between Erdogan's government and influential Muslim cleric Fethullah Gulen, who wields considerable clout in the judiciary and the police.