Reported with Colin Freeman

Violent clashes have raged on the streets of Turkey’s main cities as Mr Erdogan curbs judicial powers and sacks police officials in a battle of wills with an exiled cleric.

Mr Erdogan has sacked around 1000 police officers who were helping to carry out a bribery inquiry that engulfed the upper echelons of his party last week. Other officers have now been ordered to brief government officials on the progress of the corruption probe, which critics say will allow suspects to be tipped off in advance.

While the prime minister claims that the probe is part of a politically-motivated smear campaign, the inquiry has already led to a repeat of the anti-government rallies that took place earlier in the summer. On Monday, the European Union warned Mr Erdogan that he was in direct breach of EU rules safeguarding the independence of the judiciary, which is also a key condition for Turkey’s EU membership bid.

“The latest developments, including the sacking of police chiefs and the instructions to police to inform authorities on investigations, raise serious concerns as regards the independence, efficiency and impartiality of the investigations and the separation of powers,” said a spokesman for Štefan Füle, the European Commissioner for Enlargement. “This further highlights the need for establishing a proper judicial police as already recommended by the EU.”

The corruption probe, which has sparked a fresh crisis of legitimacy for Mr Erdogan, involves allegations of fraud, backhanders and sanctions-busting deals with neighbouring Iran. Some 24 people, including the sons of two cabinet ministers, have so far been charged in three parallel investigations.

Significantly, the people accused of instigating the conspiracy are not Mr Erdogan’s long-running enemies in Turkey’s secular establishment, but a rival faction within his own Justice and Development Party (AKP).

Suspicion has focused on followers of Fethullah Gulen, an influential Turkish cleric who lives in the United States. Mr Gulen was once one of the AKP’s main spiritual leaders, preaching a blend of moderate, business-friendly Islam that helped the party rise to power. But he is believed to have fallen out with the AKP leadership over a decision to shut down a large network of private schools that he runs in Turkey.

Mr Gulen, who is said to have a network of followers at high levels in the police force, is alleged to have instigated the corruption inquiry in revenge, although last week he denied having anything to do with it.

Mr Erdogan, 59, has earned a reputation as a combative figure during his three terms in office, but even so, his furious reaction to what many see as a legitimate police inquiry has taken many Turks aback.

On Saturday, he hinted that he might expel foreign ambassadors from the country, after accusing them of conspiring in what he has denounced as a “dark alliance” against him.

His defiant stance has already played into the hands of Turkey’s secular opposition, who say it is yet more proof of a dictator-in-waiting.

“Erdogan has gone crazy with power,” said Sevvel Kilic, one of thousands of anti-government demonstrators who attended an anti-government protest in Istanbul on Sunday, which police dispersed with tear gas and water cannon. “He is already white-washing the investigation”.

“The AKP are hypocrites,” added Timur Karadeniz, another demonstrator. “They say they are fighting corruption, but when it comes to their own corruption, they try to silence the press and the people.”