A woman holds a banner with a picture of Erdogan reading ‘Tayyip, will you shut up and let women do’ during a demonstration against corruption and the government yesterday in Istanbul.

Reuters/Istanbul

Turkish Prime Minister Recep Tayyip Erdogan swore yesterday that he would survive a corruption crisis circling his cabinet, saying that those seeking his overthrow would fail just like mass anti-government protests last summer.

Erdogan, who says that the scandal is an international plot, accused his opponents of caring not about corruption but wanting to undermine the power of Turkey, which has been transformed economically under his 11-year leadership.

On Friday, thousands of Turks demanding his resignation clashed with riot police in central Istanbul. The trouble recalled protests in mid-2013 which began over development plans for the city’s Gezi park but broadened into complaints of authoritarianism under Erdogan’s Islamist-rooted AK party.

Erdogan, who is touring Turkey to drum up support before local elections in March, defied his accusers over the detention for suspected graft of three ministers’ sons and the head of state-run Halkbank earlier this month.

“They said ‘Gezi’ and smashed windows. Now they say ‘corruption’ and smash windows. These conspiracies will not succeed,” he told a cheering crowd in western Manisa province. “Their concern is not corruption, law or justice. Their only concern is damaging this nation’s power.”

Erdogan’s government has purged about 70 police investigators involved in the case, while financial markets have taken fright and one AK official said national elections could be brought forward from 2015 if the crisis persists.

Although seven protesters and a police officer were killed in last summer’s protests, Erdogan’s popularity was almost unaffected in opinion polls.

Analysts say this was due to his strong support among pious Turks and wealthy elites, as well as the diffuse nature of those demonstrations.

However, the current affair threatens to tarnish Erdogan’s moral appeal and the crackdown on police has provoked a feud with the judiciary.

Fretting investors have dumped Turkish stocks and pushed the lira currency to an all-time low against the dollar, a slide which a cabinet reshuffle failed to halt.

The case turned more personal last week when Turkish media published what appeared to be a preliminary summons for Bilal Erdogan, one of the premier’s two sons, to testify.

Erdogan, who denies any wrongdoing, said Bilal was named to hurt him.

Friday’s unrest did not recur on Saturday or yesterday.

Unlike Erdogan’s past confrontations with rivals such as the secularist military, the corruption scandal has exposed an internecine rift among powerful religious Turks.

Erdogan’s allegations of a foreign hand in the affair put the focus on Fethullah Gulen, a Turkish cleric who preaches from self-imposed exile in the US and whose Hizmet movement claims at least 1mn followers, including senior police and judges, in Turkey.

Gulen denies involvement in stirring up the graft case. But he regularly censures Erdogan, a former ally with whom he fell out in a dispute for control over an influential network of Turkish cram schools, which prepares students for university exams.

In a vaguely phrased sermon uploaded to Gulen’s website over the weekend, the cleric likened the current situation to dark historical episodes when “the masses were the playthings of demagogues, put to sleep and awoken at will”.

He predicted the “funeral of this chaos, and the sacred days when the nation will be on a path to relief, are close”.

German Foreign Minister Frank-Walter Steinmeier called for a thorough investigation of the graft allegations in remarks published in a newspaper yesterday.

“In a region marked by crises and conflict we need Turkey as a stable anchor,” he told Bild am Sonntag. “We trust in the power of the Turkish state to investigate the corruption allegations irrespective of the persons involved. Succeeding in this is a measure of every state build on the rule of law.”