Inside the Balfour Street residence, Mr. Netanyahu was questioned for hours under caution as a possible suspect, according to the police. His wife, Sara, was questioned simultaneously as a suspect in the same case at the fraud investigation unit’s headquarters in Lod, central Israel.
The latest twist in a spiraling corruption scandal comes on the eve of Mr. Netanyahu’s departure for Washington, where he is scheduled to meet President Trump and address the American Israel Public Affairs Committee’s annual policy conference.
Mr. Netanyahu has made a point of maintaining a high-profile presence on the world stage, traveling in recent weeks to India, where he was treated like royalty; to the World Economic Forum in Davos, Switzerland; and to an international security conference in Munich.
Denying all wrongdoing, Mr. Netanyahu has been trying to project a business-as-usual approach despite his mounting legal troubles, aiming to burnish his credentials both at home and abroad as an international player.
The questioning of the prime minister, who also served as communications minister from 2014 to 2017, in this latest case was expected.
Several members of his close circle have been arrested in the case, including Nir Hefetz, a former media adviser to the Netanyahus, and Shlomo Filber, a political operative for Mr. Netanyahu’s conservative Likud Party and Mr. Netanyahu’s pick as director general of the Communications Ministry. Mr. Filber, a long-serving Netanyahu aide, has turned state witness.
The case involves a dicey mix of political power, big business and personal relationships. Mr. Netanyahu is a friend of Mr. Elovitch, who owns the Eurocom Group holding company, which owns Bezeq, the Israeli telecommunications giant that has long had a near-monopoly on land lines in the country.
Bezek owns Walla, the Israeli news site that has provided lopsidedly flattering coverage of the Netanyahus for months or years. Sara Netanyahu, a friend of Mr. Elovitch’s wife, Iris, is reported to have sent messages to her with demands to tilt the coverage in her husband’s favor. Mrs. Elovitch has already been arrested in the affair and spent several days in detention.
Mrs. Netanyahu is facing possible fraud charges in a separate case in which she is accused of misusing about $100,000 in public funds in her management of the prime minister’s official residence.
Among other things, the Communications Ministry is said to have pushed regulators to allow the merger of a money-losing satellite network, Yes, also owned by Mr. Elovitch, with Bezeq, a deal that would have reaped huge tax savings for Mr. Elovitch.
At a hearing for two of the suspects in the case in a Tel Aviv court this week, Yehudit Tirosh, a prosecution lawyer, pointed a finger at Mr. Netanyahu in his role as communications minister.
“This is a grave case of giving and receiving bribes,” Ms. Tirosh was quoted as saying by the Israeli news media. “The term ‘positive coverage’ is misleading. This is harnessing a leading website in return for regulatory favors by the minister of communications and the director general of the Ministry of Communications.” The value of the regulatory benefits was about $500 million, she said.
Mr. Netanyahu responded in a Facebook post this week, saying, “All actions were carried out in a professional manner based on the recommendations of the professional echelon, professional committees and legal counsel.’’
Jack Chen, a lawyer representing Mr. Elovitch, said in an interview on Friday that the allegations were “baseless,” and that his client categorically denied that there was ever any such deal.
Mr. Netanyahu, who has been accused of accepting nearly $300,000 in gifts over 10 years, has found himself and his close associates accused on a variety of fronts:
• Case 1000, the gifts-for-favors affair in which the police last month recommended that Mr. Netanyahu be charged with bribery, fraud and breach of trust.
• Case 2000, in which Mr. Netanyahu was suspected of back-room dealings with Arnon Mozes, publisher of the popular newspaper Yedioth Ahronoth, to ensure more favorable coverage. The police have also recommended charges in that case.
• Case 3000, which involves suspicions of corruption surrounding a multibillion-dollar purchase of submarines and other naval vessels from a German shipyard. Mr. Netanyahu is not a suspect in that case, though some of his closest confidants are.
• Case 4000, which was the subject of the police questioning on Friday.
The Walla news site has changed its tune in recent months, offering some considerably less fawning coverage of the Netanyahus.
In January, it published an earsplitting recorded telephone conversation from 2009 in which Mrs. Netanyahu could be heard berating a publicist over a short gossip column item about her participation in a school fund-raising event that did not cite her educational and professional credentials to her satisfaction.