Turkish riot police aim their weapons at protesters during an anti-government demonstration yesterday in Istanbul.

Reuters/Ankara

Turkey’s president has pledged that there would be no cover-up in a high-level corruption case, despite a government-ordered purge of police investigating it that drew protests at home and a caution from the European Union.

The week-long scandal, which erupted with the arrest for graft of 24 people including the chief of a state-run bank and the sons of two ministers, pits Prime Minister Recep Tayyip Erdogan against the judiciary and has rattled foreign investor confidence.

Erdogan, a third-term premier credited with Turkey’s economic blossoming, has portrayed the probe as a foreign-orchestrated plot against national unity.

He responded by sacking or reassigning some 70 of the police officers involved, including the Istanbul police chief.

The moves incensed many Turks who see an authoritarian streak in Erdogan and his Islamist-rooted AK Party, and took to the streets in unprecedented anti-government protests in mid-2013.

President Abdullah Gul, a more unifying figure, sought to calm the furore.

“Turkey is not the same place compared to 10 or 15 years ago. Many reforms have been carried out, in politics as well as in the law,” Gul said in his first public remarks on the case.

“In a country where such reforms have taken place, if there were corruption and mistakes they would not be covered up,” he told reporters, adding that “the independent, objective and democratic legal system (will) adjudicate the allegations in a manner that will not leave any question marks”.

The corruption investigation centred on Halkbank was conducted largely in secret.

At the weekend, the Erdogan government changed regulations for the police, requiring officers to report evidence, investigations, arrests and complaints to commanding officers and prosecutors.

Journalists have also been barred from police buildings.

Thousands of Turks demonstrated in Istanbul on Sunday, calling on the government to resign.

AK Party supporters countered with rallies in which they wrapped themselves in mock burial shrouds to show they would back Erdogan “to the death”.

Yet there were misgivings within the AK Party.

One AK Party lawmaker, Haluk Ozdalga, was quoted by local media as saying: “To give the executive organs such a large opportunity to intervene greatly violates the independence of the judiciary”.

The European Union, to which Turkey has long tried to gain accession, voiced worry too.

“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,” a spokesman for Stefan Fule, the European Commissioner for Enlargement, said in remarks published by Britain’s *Daily Telegraph newspaper on Monday. “This further highlights the need for establishing a proper judicial police as already recommended by the EU.”

Erdogan is no stranger to quarrels.

He transformed Turkey by curbing the military – guardian of the Nato power’s secularist constitution – and champions an often aggressive foreign policy.

The latest scandal has laid bare a more intimate rivalry between Erdogan and Fethullah Gulen, a US-based Turkish cleric whose Hizmet (“Service”) movement claims at least 1mn followers, including senior police and judges, and runs schools and charities across Turkey and abroad.

While denying any involvement in the affair, Gulen has taken personally to Erdogan’s descriptions of Hizmet as a “dirty operation” against Turkey that is controlled by shadowy foreign forces.

Raising the rhetorical temperature, Gulen on Monday dismissed Erdogan’s statements as “nothing but a reflection of decayed thinking”.