Story highlights Journalists who cover police beat are ordered to hand in credentials

Police say any time they have a statement to make, reporters will be invited in

Veteran reporter fears this is a hint of more restrictions on journalists to come

Ban comes in the midst of a corruption probe, purge of police commanders, and political turmoil

Turkish authorities Sunday announced a ban on journalists entering police stations, in the midst of a government purge of dozens of police commanders.

The wholesale dismissal of scores of senior police officers in recent days appears to be retaliation for the arrests of the sons of two Cabinet ministers, as well as dozens of other suspects, in a corruption investigation that Turkey's prime minister claimed is a "dirty, dirty operation" aimed at toppling his government.

Journalists accredited with the Turkish police have been ordered to hand in their credentials as well as keys to the media briefing rooms in some police stations. "If there are any developments or press statements press members will be invited," read a statement from the police.

Reporters who had long worked the police beat said the ban was unprecedented.

One veteran police reporter, who spoke to CNN on the condition of anonymity for fear of reprisal, said the ban was the first of its kind during a 16-year career.

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Photos: Protest in front of Turkish bank Photos: Protest in front of Turkish bank Bank scene of Turkish protest – Thousands of demonstrators chanted "help, there are thieves" during the protest in front of a branch of the state-owned Halkbank. Hide Caption 1 of 3 Photos: Protest in front of Turkish bank Bank scene of Turkish protest – An ATM machine was targeted during the protest. Hide Caption 2 of 3 Photos: Protest in front of Turkish bank Bank scene of Turkish protest – Some activists demonstrated with shoe boxes in front of the bank. Hide Caption 3 of 3

"It was very surprising to me. On the one hand you talk about press freedom, then you ban the press from police stations. It is very bizarre," the reporter said.

"Imagine you're a police beat reporter, how do you do your job?" the journalist added. "So they are going to invite us for the stories they want us to write, then when there is a corruption probe they are going to say don't come."

The journalist feared this was the beginning of more severe measures that the government may take in trying to silence coverage.

"This is a forewarning of bigger precautions they are going to take, that they are going to take even more serious steps. Everything aside, this is them trying to completely eradicate the position of the media," the reporter said.

Turkey already has a dismal ranking when it comes to freedom of the press. According to a number of international press freedom groups, Turkey is the No. 1 jailer of journalists.

Sunday's police press ban comes at the end of a week of political turmoil that has shaken the value of the Turkish lira and unsettled the Istanbul stock market.

Turkey's Prime Minister Recep Tayyip Erdogan appears to be in an open power struggle with a former political ally, Fethullah Gulen. Gulen is an Islamic cleric living in self-imposed exile in Pennsylvania, whose supporters are thought to be key in positions within the police force and the judiciary.

Top government officials accused Gulen recently of trying to establish a "parallel state" within the Turkish government. They have also justified the purge of police officers by accusing them of carrying out the corruption arrests outside of the chain of command.

According to press reports, Interior Minister Muammer Guler, who controls the police force, had no prior knowledge of the corruption probe which led to the arrest of his son and the son of the economy minister. In his first statement since the arrests, Guler denied any wrongdoing. "We have no illegal doings, there is nothing we cannot account for. Everything will be revealed in the coming days," he wrote on his official Twitter account.

Erdogan has repeatedly claimed, since the corruption probe began on Tuesday, that international organizations with branches inside Turkey are trying to destabilize the country.

"This country has never been and never will be the operational space of international organizations. We will not allow the interest lobby, the war lobby, the blood lobby to carry out an operation under the guise of a corruption operation," he said during a speech on Sunday in the Black Sea town of Giresun. The speech echoed similar accusations Erdogan made when he blamed an unidentified "interest lobby" for organizing mass anti-government demonstrations that roiled the country in June.

On Saturday, Gulen fired back at the government in a videotaped sermon released on one of his movement's websites.

He denied links to the police officers and prosecutors carrying out the corruption investigations but also sent a fiery warning laced with religious rhetoric.

"Those who don't see the thief but go after those trying to catch the thief, who don't see the murder but try to defame others by accusing innocent people, then may God bring fire to their houses, ruin their homes, break their unity," Gulen said.

Last month, Erdogan announced that he would shut down college admission tutorial centers, a decision denounced by the Gulen movement. Gulen presides over an international network of schools and universities, in addition to the Turkish prep schools that would be closed by Erdogan's new policy. Soon after, Hakan Sukur, an ex-soccer star and member of parliament from Erdogan's ruling political party, resigned in protest.

Turkey is expected to hold nationwide muncipal elections in March. After widespread anti-government protests over the last year and now an open battle against a former ally, many political analysts in Turkey see the coming elections as a test of Erdogan's grip on power.

On Sunday, thousands of demonstrators chanted "Help, there are thieves" at an authorized anti-government protest in Istanbul's Kadikoy district.

Some activists demonstrated with shoe boxes in front of a branch of the state-owned bank Halkbank.

The director general of the bank was arrested on Saturday in conjunction with the corruption investigation. Turkish media reported police found millions of dollars in cash stored in shoe boxes in the banker's home.