* Five departmental police chiefs reassigned
* Government supporters see smear campaign
* Prosecutor says conducting three probes (Adds Erdogan meeting, quotes, details)
By Humeyra Pamuk and Ece Toksabay
ANKARA/ISTANBUL, Dec 18 (Reuters) - Five senior Turkish police officers have been sacked a day after scores of people close to government were detained in an anti-corruption crackdown, local media said on Wednesday, in an apparent power struggle shaking the country's ruling elite.
Scores of people including three ministers' sons, prominent businessmen close to Prime Minister Tayyip Erdogan and local government officials were detained on Tuesday in the biggest corruption investigation since Erdogan swept to power in 2002.
It threatens the authority of a man who has dominated Turkey for more than a decade, as well as the reputation of his AK Party, months before important local elections. It was widely seen in media as symptom of a power struggle with a U.S.-based preacher who commands influence in party, police and judiciary.
The heads of five departments in the Istanbul police force, including its financial crimes, organised crime and smuggling units, were removed from their posts and swiftly replaced following the detentions, Turkish newspapers said.
In a brief statement the police said it had reassigned some staff, in some cases due to alleged misconduct and others "out of administrative necessity", but gave no further details.
"If this is an effort to obstruct the healthy enforcement of the investigation, of course it would not be right," Finance Minister Mehmet Simsek told reporters in Ankara, when asked about the issue, but said he could not confirm the changes.
Turkey, a NATO member, commands a strategically sensitive position bestriding Europe and the Middle East. Under Erdogan it had achieved a great deal of economic and political stability, though the past year as seen unprecedented protests against what some see as an authoritarian style of government.
The corruption investigation dominated newspaper headlines, with many commentators linking it to a deepening rift between Erdogan and the U.S.-based preacher Fethullah Gulen.
Pro-government newspapers accused Gulen's followers of running a smear campaign against the AK Party ahead of March local elections, due to be followed a few months later by a presidential race in which Erdogan is expected to run.
"The black propaganda escalates," the daily Star newspaper said on its front page. "Somebody has pushed the button on the eve of the municipality elections."
KEY ADVISERS MEET
Erdogan assembled key advisers, including two deputy prime ministers and his interior and justice ministers, for an unscheduled meeting in Ankara, AK Party officials said, but declined to comment on what was discussed.
In its first official comment since Tuesday's dententions, the Istanbul prosecutor's office said it was conducting three separate investigations and that two additional prosecutors had been appointed to assist.
It said the latest actions were part of long-standing investigations, two of which started in September 2012 and the third in February this year.
HEART OF THE RULING PARTY
Erdogan and Gulen both draw support from religiously minded, conservative Turks but there have long been ideological differences which have bubbled increasingly to the surface.
Erdogan has infuriated Gulen supporters with plans in recent weeks to abolish private "prep" schools, many of which are run by their Hizmet (Service) movement and which provide both funding and new followers.
Gulen could not challenge Erdogan at the polls and has shown no intention of forming a party, but their battle for influence could shape Turkish policy for years to come.
Many of Gulen's followers see him as a more progressive and pro-Western influence than Erdogan, whose opinions on issues from abortion to alcohol consumption and concentration of power around himself they view with increasingly alarm.
"This does mark a battle for the heart and mind of the party, and for the likely policy orientation," said Timothy Ash, head of emerging markets research at Standard Bank.
Gulen runs a network of schools and other social facilities across the Middle East, Asia and Africa from a compound in the United States. He moved to the United States in 1999 after being charged with attempting to undermine the secular state.
He was later acquitted but has remained in Pennsylvania, an enigmatic figure who gives little hint of his intentions in Turkish politics.
Erdogan has built his own body of wealthy loyalists, largely from the same religiously minded professional class that reveres Gulen, since he came to power in 2002.
(Writing by Nick Tattersall; editing by Ralph Boulton)