The Turkish government has dismissed 350 police officers in Ankara, local media reports say, in the latest twist in a corruption scandal embroiling powerful politicians.

The officers were sacked on Tuesday by a government decree published at midnight and included chiefs of the financial crimes, anti-smuggling, cyber crime and organised crime units, the private Dogan News Agency reported.

The move comes as the government is trying to contain the political fallout from the fraud probe that has become the biggest threat to Recep Tayyip Erdogan's 11-year rule in the run-up to local elections in March.

The Turkish prime minister has branded the investigation a "dirty plot" to try to topple his government, blaming supporters of a powerful exiled Turkish religious leader who wields considerable influence in the judiciary.

Fethullah Gulen, which exercises influence through a network of contacts built on sponsorship of schools and other social and media organisations, and Erdogan accuse each other of manipulating the police and compromising the independence of the judiciary.

No Backing down

Dozens of leading businessmen and political figures, including the sons of three ministers, were rounded up in a sweep in Ankara and Istanbul in December.

Erdogan responded by sacking hundreds of police officials across the country, including the powerful Istanbul police chief.

Separately, Erdogan said on Sunday he would favour retrials for hundreds of military officers jailed for alleged coups plots against his government.

Erdogan's critics accuse him of desperately trying to protect his cronies, and the appointment of Selami Altinok, a little-known governor with no background in police work, as Istanbul's new police chief was further seen as an attempt to shut down the investigation.

With the latest round of dismissals, the total number of police officers removed from their posts has risen to 560 in Ankara alone, according to media reports.

Muammer Akkas, a prominent prosecutor, was barred last month from expanding the investigation, which could also reportedly target Erdogan's son Bilal over allegations he leaked information to the media.

The corruption crisis erupted on December 17 when police arrested dozens of people, including sons of former ministers and the chief executive of Turkey's state-run Halkbank.

They are suspected of numerous offences including bribery for construction projects and illicit money transfers to sanctions-hit Iran.

Police have conducted further raids in five cities and detained 25 people on suspicion of bribery and fraud in tenders for construction projects, including civil servants from the Turkish rail authority TCDD and the western port of Izmir, local media said.

The corruption scandal is shaking investor confidence at a time when the lira currency is languishing around record lows, inflation is rising and growth slowing.

As much as its Islamist-rooted ideology, the AKP has relied on its avowed commitment to fight corruption and its economic record for public support.