Israel's attorney general formally charged Prime Minister Benjamin Netanyahu in a series of corruption cases Thursday. The indictment throws the country's paralyzed political system into further disarray and threatening the long-time leader's grip on power.

Capping a three-year investigation, Attorney General Avichai Mandelblit charged Netanyahu with fraud, breach of trust and accepting bribes in three different scandals. It's the first time a sitting Israeli prime minister has been charged with a crime.

Addressing reporters Thursday, Mandelblit said the indictment was a "heavy-hearted decision" based solely on professional considerations. He rejected suggestions that the indictment was politically motivated.

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"A day in which the attorney general decides to serve an indictment against a seated prime minister for serious crimes of corrupt governance is a heavy and sad day, for the Israeli public and for me personally," he told reporters.

Israeli Prime Minister Benjamin Netanyahu seen November 20, 2019. Getty

According to the indictment, Netanyahu accepted hundreds of thousands of dollars of champagne and cigars from billionaire friends, offered to trade favors with a newspaper publisher and used his influence to help a wealthy telecom magnate in exchange for favorable coverage on a popular news site.

The indictment does not require Netanyahu to resign but is expected to raise pressure on him to step down.

Netanyahu has called the allegations part of a witch hunt, lashing out against the media, police, prosecutors and the justice system.

The most serious charges were connected to so-called "Case 4000," in which Netanyahu is accused of passing regulations that gave his friend, telecom magnate Shaul Elovitch, benefits worth over $250 million to his company Bezeq. In return, Bezeq's news site, Walla, published favorable articles about Netanyahu and his family.

The relationship, it said, was "based on a mutual understanding that each of them had significant interests that the other side had the ability to advance." It also accused Netanyahu of concealing the relationship by providing "partial and misleading information" about his connections with Elovitch.

Two close aides to Netanyahu turned state's witness and testified against him in the case.

Here's a look at the other cases concerning the prime minister:

Lavish gifts

Police recommended indicting Netanyahu over accepting nearly $300,000 in gifts from Hollywood mogul Arnon Milchan and Australian billionaire James Packer.

Police say that in return for jewelry, expensive cigars and champagne, Netanyahu operated on Milchan's behalf on U.S. visa matters, tried to legislate a generous tax break for him and sought to promote his interests in the Israeli media market.

Police have not commented on what Packer, who reportedly sought Israeli residency status for tax purposes, may have received, and Netanyahu has said all he received were gifts from friends. Longtime aide Ari Harow is a state witness in this case. The charges include fraud and breach of trust.

Media meddling

Police have also recommended indicting Netanyahu for offering a newspaper publisher legislation that would weaken his paper's main rival in return for more favorable coverage.

Netanyahu reportedly was recorded asking Arnon Mozes, the publisher of the Yediot Ahronot daily, for positive coverage in exchange for helping to weaken Israel Hayom, a free pro-Netanyahu newspaper that had cut into Yediot's business.

Israel Hayom is financed by Netanyahu's American billionaire friend Sheldon Adelson and largely serves as the prime minister's mouthpiece. Netanyahu has noted that a proposed law to weaken Israel Hayom never passed and that he had even dissolved his coalition and called a new election in 2015 because of his opposition to the proposal. Harow is a state witness in this case, too.

According to TV reports based on recently leaked police investigations, Adelson's wife also testified that Sara Netanyahu exerted pressure on her to provide gifts and favorable media coverage. The charges include fraud and breach of trust.