ISTANBUL : Turkish authorities on Monday detained some two dozen police officers in new nationwide raids over an alleged plot to overthrow the Islamic-rooted government of President Recep Tayyip Erdogan.

Police conducted early morning raids in 16 cities across Turkey, including Istanbul as well as the western province of Izmir, and detained at least 20 police officers, private NTV television reported.

Among those arrested is Yakup Saygili, the former chief of the police anti-fraud unit, it added.

It was the fourth such wave of raids since July as the government cracks down on what Erdogan has described as a “parallel state” within the security forces seeking to topple his government.

Arrest warrants were issued for at least 34 officers accused of a number of offences including illegally eavesdropping on top officials and attempting to overthrow the government.

Since July, dozens of police officers have been arrested and placed in custody on suspicion of forming a criminal organisation and wire-tapping hundreds of people including Erdogan.

The new arrests appeared to represent a new offensive against the movement of Erdogan’s former ally Fethullah Gulen in the wake of a vast corruption scandal that broke late last year implicating Erdogan and his inner circle.

Erdogan has long accused followers of US-based Muslim cleric Fetullah Gulen of establishing a “parallel state” by using its sway in Turkey’s police and the judiciary and of concocting the vast corruption scandal.

The allegations were based on recorded phone conversations - purportedly of Erdogan and his inner circle - whose publication held much of Turkey in thrall.

Gulen, who has been based in the United States since 1999, denied any involvement in the claims.

By coincidence, Istanbul prosecutors announced Monday they were dropping all legal proceedings against 96 people probed as a result of the corruption allegations, including Erdogan’s son Bilal.

Erdogan on Thursday moved from the office of prime minister to president after his August 10 election victory, with his close ally, former foreign minister Ahmet Davutoglu, taking the post of premier.

Erdogan had said Davutoglu was chosen due to his “determination to fight” the parallel state.

Speaking at Istanbul airport before leaving on his first foreign trip as head of state, Erdogan said more operations could follow to arrest additional suspects.

“As you know it is only part of the process. It is not the end,” saying there could be a new wave “if new information or evidence emerge.”

“We are following this process very closely,” he said.

Since the allegations first broke, the government has already moved to purge opponents from the security forces and increase its control over appointments in the judiciary.

In a speech Monday, Turkey’s top judge issued a thinly-veiled warning to Erdogan to refrain from interfering in the judiciary.

“A judicial authority that is under the influence of the executive cannot correctly fulfil its role which is to prevent arbitrariness and illegality,” said the president of Turkey’s supreme court, Ali Alkan, in a speech marking the opening of the judicial year.

In a sign of the tensions between the government and the judiciary, both Erdogan and his Prime Minister Ahmet Davutoglu shunned the event to mark the new judicial year, which they would normally be expected to attend.