Three Turkish Cabinet ministers resigned Wednesday amid a growing bribery scandal that has even prompted members of Prime Minister Recep Tayyip Erdogan's party to call for his resignation.

Economy Minister Zafer Çaglayan and Interior Minister Muammer Güler stepped down early Wednesday, with both of them denouncing a judicial probe targeting their sons, among others, as a plot aimed at sinking Erdogan's government.

Environment and Urban Planning Minister Erdogan Bayraktar resigned - from that post and his seat in Parliament - shortly afterward, telling the NTV television network that most of the construction projects under suspicion in the probe had been approved by the prime minister.

"It's my conviction that to bring tranquility to our country the prime minister also should resign," Bayraktar said.

Kaan Çaglayan and Baris Güler, sons of the economy minister and interior minister, respectively, were arrested on bribery charges earlier this month and remain jailed, while Abdullah Oguz Bayraktar, son of the now former environment minister, was detained and subsequently released but still faces charges.

Erdogan said in a long speech to the provincial presidents in Ankara that the judicial probe was "an international conspiracy" motivated by the desire of the "financial lobby" to raise interest rates and the envy provoked by the planned construction of the world's third-largest airport in Istanbul."

He compared the investigation to anti-government protests that began in late May to protest an urban-development plan at Istanbul's Taksim Gezi park.

Erdogan said the "nine-day judicial investigation had cost Turkish companies $20 billion" due to plunging share prices and provoked losses totaling $1.63 billion at state-run bank Halkbank, whose director is among 24 suspects jailed in the bribery probe.

The prime minister pledged to fight against "the gangs that operate in Turkey under the cloak of religion," a thinly veiled reference to the movement led by exiled Muslim preacher Fethullah Gülen, who is living in the United States and has numerous supporters within Turkey's judiciary and police force.

"We won't let a parallel state be established," he pledged, referring to the well-structured "Gülenist" network, which until this summer had backed Erdogan's AKP's party and was likely a key factor in helping him win re-election for the third time in 2011.

Gülen, for his part, has denied any link to the judicial inquiry.

The probe is centered on two aspects, according to analysts: purported money laundering related to Turkish payments for imported oil from sanctions-hit Iran, transactions allegedly facilitated by Halkbank, and the awarding of lucrative state contracts for land development. EFE