A police statement said that Netanyahu was questioned for over five hours under caution at his Jerusalem residence over allegations he illegally accepted gifts from wealthy foreign businessmen as well as over another corruption affair, which some Hebrew media reports have said is more "serious".
Investigators have kept a tight lid on the other case.
Police confirmed they have interrogated a second suspect, whose identity was not revealed.
"Nothing will come (of the probe) and you will continue to spew out hot air," the prime minister said mockingly.
In a three-hour interrogation session with police on Monday, the Israeli premier admitted that he had received gifts from businessmen, but insisted they were entirely legal, his lawyer said.
Hebrew media reported that police are investigating suspicions that Netanyahu and his wife Sara illicitly accepted cigars worth hundreds of thousands of shekels and champagne from American-Israeli Hollywood producer Arnon Milchan.
Channel 2 news reported last evening that Netanyahu received the cigars from Milchan over the last 7-8 years.
Sara reportedly received bottles of pink champagne worth hundreds of shekels apiece during that period.
Netanyahu is known as a connoisseur of fine cigars and the channel pointed out rumours that he smokes tens of thousands of shekels worth of them each month.
Attorney General Avichai Mandelblit, who is overseeing the investigation against Netanyahu, has said the premier is suspected of "receiving improper benefits from businessmen".
The statement chronicled the inquiry but did not provide details of the nature of suspicions in the graft case.
The police has been examining "a long list of claims" against the premier since July, Mandelblit said.
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Ron Lauder, a Jewish American businessman and an old friend of Netanyahu, was one such witness.
Lauder confirmed to police that he had given Netanyahu various gifts, including a suit, and that he had also financed a trip abroad for the prime minister's son, Yair.
Netanyahu has strongly denied all allegations against him.
"All previous so-called affairs have proved baseless and so it will be with the allegations now published in the media. They won't come to anything, because there isn't anything," Netanyahu earlier said.
Former Israeli prime minister Ehud Olmert is serving a jail term on charges of graft. Netanyahu had succeeded Olmert in 2009 after he resigned when a series of graft charges were brought against him.
