Turkish Prime Minister Tayyip Erdogan reshuffled his cabinet on Wednesday, Dec 25 after three members quit over a corruption scandal that has posed an unprecedented challenge to his 11-year rule, according to Reuters.

The crisis erupted on December 17 when dozens of people, including of the head of state-run Halkbank, were arrested on graft charges. Erdogan responded by purging police investigators. The ensuing feud with the judiciary reignited long-simmering street protests and rattled foreign investors.

Earlier on Wednesday, three ministers who had sons among those detained resigned. Two of them echoed Erdogan in depicting the inquiry as baseless and a conspiracy. The third, Environment Minister Erdogan Bayraktar, turned on the premier.

"For the sake of the wellbeing of this nation and country, I believe the prime minister should resign," he told NTV news.

By breaking ranks, Bayraktar may have diluted any easing of pressure on Erdogan afforded by the ministers' resignations, although some commentators thought their timing was off.

"These are very late and difficult resignations. They don't have any value in terms of democracy," said Koray Caliskan, an associate professor at Istanbul's Bogazici University.

After nightfall, a spent-looking Erdogan announced he was appointing 10 new ministers to replace the three who quit and others planning mayoral runs in local elections in March.

The fact that the shake-up happened over Christmas cushioned the blow to Turkey on dormant international markets. But the stock index closed 4.2 percent and the lira weakened to 2.0862 against the dollar.

During his three terms in office, Erdogan has transformed Turkey by tackling its once-dominant secular military and overseen rapid economic expansion. He weathered anti-government demonstrations that swept Istanbul and other cities in mid-2013.

The gauntlet thrown down by Bayraktar set off fresh protests in Ankara, Istanbul and Izmir. Erdogan was unmoved.