Turkey PM faces resignation call as three ministers quit in corruption scandal He said a great proportion of the construction contracts being investigated by the police were approved by his boss. "For the sake of the wellbeing of this nation and country, I want to express my belief that the esteemed prime minister should also resign," Mr Bayraktar said. The investigation focuses on a find of the equivalent of $4.5 million (£2.75 million) found stashed in shoe boxes in the home of the chief executive of the state-run Halkbank. Among the at least 25 people arrested were Salih Khan, the son of the economy minister, Zafer Caglayan, and Baris Guler, the son of the interior minister, Muammer Guler, in whose house a further $1 million (£600,000) was found. Fethullah Gulen (Reuters) The allegations are that the sons were taking bribes on behalf of their fathers, something all three men deny. Mr Bayraktar's son, Abdullah Ogaz, was detained but has subsequently been released. Mr Guler claims that wiretaps implicating his son had been tampered with and the $1 million found in his home was the proceeds of the sale of a villa. Mr Erdogan has been claiming that "foreign countries" and other malign forces have been plotting against his government since violent protests against his government beginning in Istanbul swept the country in June. Protestors clash with Turkish police in Istanbul on Sunday (AFP) His fury in this case was worsened by the surprise element - the police had been investigating for more than a year without his government being aware of it. His immediate reaction was to order a thorough purge of senior police ranks. The secular opposition has accused him of becoming too involved in the Islamist politics of the Arab Spring and of attempting to end Turkey's role as a model of secularism in the Muslim world. But analysts say this case may be the fall-out of a clash within the broader Islamist movement, with Mr Erdogan having fallen out with Fethullah Gulen, the US-based founder of a religious educational and charitable organisation which has followers throughout the Turkish establishment.