Turkish police chiefs who reportedly oversaw a wave of high-profile arrests for bribery have been removed from their posts in Istanbul.
Five police chiefs were removed in Istanbul a day after 52 people were picked up, including three sons of cabinet ministers.
A senior member of the government suggested the investigation was aimed at "tarnishing" its reputation.
But Deputy PM Bulent Arinc stopped short of blaming any particular group.
The arrests are being seen by correspondents as part of a feud between Prime Minister Recep Tayyip Erdogan's government and an influential former ally, the US-based Islamic preacher Fethullah Gulen.
Mr Gulen once backed the ruling AK Party, helping it to victory in three elections since 2002, and members of his Hizmet movement are said to hold influential positions in institutions from the police and secret services to the judiciary and the AK Party itself.
In recent months, the alliance began to come apart and in November the government discussed closing down private schools, including those run by Hizmet.
In a speech after Tuesday's wave of arrests, Mr Erdogan vowed not to bow to any "threat" or "dirty alliances" aimed at creating division within the ruling party.
"Turkey is not a banana republic or a third-class tribal state," he said, speaking in the city of Konya, an AK stronghold. "Nobody inside or outside my country can stir up or trap my country."
But Mr Erdogan appears to have alienated a crucial element of his electoral support and his undeclared ambition to run for president in 2014 may be under threat, the BBC's James Reynolds reports from Istanbul.
'Abuse of powers'
The five police commissioners sacked include the heads of the financial crime and organised crime units, who were both involved in the earlier arrests, the Turkish daily Hurriyet reports.
Also dismissed were the heads of the smuggling unit, the anti-terrorism branch and the public security branch, the paper says.
In a brief statement, the police said they had reassigned some staff, in some cases due to alleged misconduct and others "out of administrative necessity".
The officers had "abused their powers", police were quoted as saying by AFP news agency.
The mass arrests were carried out as part of an inquiry into alleged bribery involving public tenders.
The sons of Interior Minister Muammer Guler, Economy Minister Zafer Caglayan and Environment Minister Erdogan Bayraktar were among those detained.
Police also raided the Ankara headquarters of one of Turkey's biggest banks, state-run lender Halkbank, and the headquarters of a large construction company owned by tycoon Ali Agaoglu.
Police searching the home of detained Halkbank general manager Suleyman Aslan have found $4.5m (£2.7m; 3.2m euros) in cash hidden in shoe boxes in his library, Turkey's Dogan news agency reports.
The arrests were made as part of three separate investigations, according to Hurriyet
- An inquiry into allegations of a crime ring involving Azeri businessman Reza Zarrab (arrested), in which cabinet ministers were bribed in order to cover suspicious money transactions to Iran through Halkbank, and to obtain Turkish citizenship
- An inquiry into Abdullah Oguz Bayraktar (arrested), son of the environment minister, on suspicion that he set up a crime ring and accepted bribes from major firms in exchange for construction permits in areas under the ministry's supervision
- An inquiry into allegations that protected areas of Istanbul's Fatih district were developed illegally in return for bribes and that district mayor Mustafa Demir (arrested) allowed the construction of a hotel, ignoring negative reports from engineers and state institutions
There was no response to the allegations by those arrested.
Mr Arinc insisted the government would not intervene in the investigation.
"The judicial process should be concluded swiftly and carefully," he said. "We will always respect any decision made by the judiciary and will not engage in any effort to block this process."
Fethullah Gulen has been living in the US since 1999, when he was accused in Turkey of plotting against the secular state.