Opposition leader MK Binyamin Netanyahu (Likud) was questioned for hours by the National Fraud Squad Tuesday afternoon under suspicion of accepting gifts illegally, as his political rivals kept their eyes on the investigation of a man who sought to portray his party as the alternative to corrupt politics. Tuesday's questioning was part of an ongoing National Fraud Squad investigation into Yisrael Katz, the former chairman of the Pedagogic Secretariat at the Education Ministry, who has been accused of using government funds to support his private research institute which he ran while he worked for the ministry. For a number of months, detectives have been probing allegations that Katz committed both fraud and violation of trust in diverting Education Ministry funds to carrying out political opinion polls at the Institute for Education and Community Research at Bar Ilan University. In this case, Netanyahu is suspected of receiving opinion polls conducted for him by Katz without compensating Katz for the service. Only after a Channel 10 report revealed in late 2005 that Netanyahu had been receiving the polling data, he paid the bill - tens of thousands of shekels - to Katz. It remains unclear if Netanyahu knew that the studies were allegedly financed through the government funds. Netanyahu's office responded Tuesday that he had paid tens of thousands of shekels from his private funds for the polls which were conducted by Professor Katz. According to them, as soon as Netanyahu was informed that the bill had not yet been paid, he instructed his attorney - David Shomron - to take care of the matter so as not to leave an open bill. Netanyahu's office added that the payments had been made "a year or a year-and-a-half ago." They did not, however, explain why - in the four years preceding the Channel 10 expose - Katz had never submitted a bill to Netanyahu for his services. Netanyahu was one of a number of witnesses questioned Tuesday at the unit's Bat Yam offices. Police sources said that Netanyahu was questioned with regard to the means by which polls which were conducted for him in recent years were funded. Netanyahu was questioned under warning after detectives received the go-ahead from Attorney-General Menahem Mazuz, who must okay any instance in which a member of Knesset is questioned. Netanyahu has recently made an effort to portray the Likud as the cleanest party in politics, particularly in contradistinction to Kadima. To that end, he moved the election of would-be MKs away from the Central Committee because it had a reputation of being corrupt. But despite the effort, Netanyahu's investigation - in addition to ongoing investigations into MKs Yisrael Katz and Chaim Katz - means that three of the 12 Likud MKs are currently under investigation. Netanyahu's political rivals were quick to realize the political potential of the investigation. "For the who-knows-what-time, Bibi's audacity and hypocrisy have been revealed once again. Only a few weeks ago, he demanded that whoever is involved in corruption not be elected. Accordingly, he must accept his own judgment and not run for elections." Said MK Yoel Hasson (Kadima). This is the second time that the National Fraud Squad is investigating Netanyahu for illegal receipt of gifts, and although the first investigation was closed without an indictment delivered, a recent public opinion poll revealed that Israeli voters still rank Netanyahu high on the corruption index. The investigation is still underway, and police said Tuesday evening that they expected more people to be questioned in connection with the investigation. Katz was appointed to the ministry by then-Minister Limor Livnat (Likud) and resigned in June - a half-year after the expos - claiming that he could not reconcile himself with the education policies of incoming Education Minister Yuli Tamir (Labor).