Prime Minister Tayyip Erdogan urged Turks to rally around him in fighting what he termed a dirty plot by foreign-backed elements targeting "the bread on your table, the money in your pocket, the sweat of your brow".
"History will not forgive those who have become mixed up in this game," Erdogan said in a televised end of year address devoted almost entirely to a corruption investigation he says has been engineered in police and judiciary to undermine his government and sap its influence in the Middle East and beyond.
Police raided offices and homes and detained businessmen close to the government and the sons of three ministers on Dec. 17. Erdogan responded by purging some 70 officers connected with the inquiry and blocking a second investigation into big infrastructure projects promoted by Erdogan.
"I invite every one of our 76 million people to stand up for themselves, to defend democracy and to be as one against these ugly attacks on our country," he said.
The scandal poses the biggest challenge to Erdogan in 11 years as leader, raising fears of a fracture in his AK Party in the run-up to elections and damage to strong economic growth.
It also pitches him against a U.S.-based Turkish cleric with strong influence in the police and judiciary, accused by Erdogan's backers of conniving at the investigation. The former ally, Fethullah Gulen, denies the allegation.
"Whichever party you support, this plot targets all of you without exception, the bread on your table, the money in your pocket, the sweat of your brow," he said.
Erdogan, who has won three elections, casts the scandal as a campaign by domestic dark forces and foreign financial organisations, media and governments resentful of a foreign policy more independent of NATO and the United States.
"Circles uncomfortable with Turkey's successes, its growing economy, its active foreign policy, its global-scale projects, implemented a new trap set against Turkey," Erdogan said, sitting at a desk before the red Turkish national flag.
Erdogan also said the investigation aimed to undermine "the picture of brotherhood" in a fragile peace process with Kurdish militants, launched in 2012 and aimed at ending a conflict which has killed 40,000 people.
Erdogan said June anti-government protests across Turkey, triggered by a heavy-handed police crackdown on a demonstration against plans to redevelop Istanbul's central Gezi Park, were part of the same conspiracy.
"Just as the Gezi incidents were dressed up in the cover of trees, parks and the environment, the Dec. 17 plot was hidden in the cover of corruption."
He said it was no coincidence that the attacks coincided with what he called one of the most successful years in modern Turkey's 90-year history. The year has seen record highs in Turkish financial markets, credit rating upgrades and the paying off of the country's IMF debt.
Erdogan's supporters argue the graft accusations have so far lacked any substance.
President Abdullah Gul, seen as unifying figure who has largely stayed out of the furore, made an appeal for unity in his New Year's message, emphasising a need for an independent judiciary free of pressure from any side.
Erdogan closed his address on a defiant tone, saying 2014 would be a year in which accession talks with the European Union would move forward and democratic reforms gather pace.