After announcing his own resignation, Environment Minister Erdogan Bayraktar raised the stakes by calling on Prime Minister Recep Tayyip Erdogan to follow suit. It marks the first time Erdogan has faced such a challenge from a minister in his own Justice and Development Party (AKP).
"I am stepping down as minister and lawmaker," Bayraktar told the private NTV television. "I believe the prime minister should also resign."
The sons of both ministers are among the two dozen people who have been charged as part of a wide-ranging bribery and corruption probe that has ensnared close government allies and top businessmen, including the chief executive of state-owned Halkbank.
Bayraktar's son was also detained last week, but has not been formally charged and has been released pending trial.
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Those caught up in the police raids are suspected of numerous offences including accepting and facilitating bribes for construction projects and illegally smuggling gold to Iran.
In a televised speech today, he did not comment on the ministers' resignations. Instead, he again blamed the probe on "a conspiracy" and "international powers" and insisted the AKP had a clean record.
Observers say the investigation has exposed a rift between Erdogan and former ally Fethullah Gulen, a Muslim cleric who lives in the United States and whose movement wields considerable influence in Turkey's police and judiciary.
The damaging probe comes ahead of crucial local elections in March and presidential elections in August.
"It's the prime minister's natural right to work with or remove whichever minister he would like to," he told NTV in a live broadcast.