Netanyahu at meeting
Netanyahu at meetingFlash 90

Israeli Prime Minister Binyamin Netanyahu underwent a new round of questioning on Friday over one of several graft cases that have threatened to topple him.

The veteran premier's 12th round of questioning as a suspect in various cases comes two days before his wife Sara appears in court on charges of misusing state funds for catering at their official residence.

The prime minister has not been charged in any of the cases.

Netanyahu has been repeatedly questioned over allegations involving Israeli telecoms giant Bezeq and its largest shareholder, Shaul Elovitch.

The premier is accused of seeking favorable coverage from another Elovitch company, the Walla! news site, in exchange for policies that could have benefited the mogul's interests to the tune of hundreds of millions of dollars.

Netanyahu also faces interrogation as a witness in a case involving the purchase of three German submarines.

Israeli television on Friday showed footage of police officers arriving at his office.

Israel Police announced the end of the questioning, but did not provide further details.

Israeli media reported that Friday's questioning will for the first time cover two further cases in which he is suspected of corruption, fraud and breach of trust.

In one, he and family members are suspected of receiving around 1 million shekels ($275,000) worth of luxury cigars, bottles of champagne and jewelry in exchange for financial or personal favors.

Netanyahu does not smoke.

In the second, he is suspected of seeking a deal for positive coverage from Israel's top-selling daily newspaper, Yediot Aharonot, in exchange for advancing a law that would have limited the circulation of Israel Hayom, a free competitor.

His wife Sara appears in court on Sunday charged with misusing state funds to buy catered meals costing $100,000 (85,000 euros) by falsely declaring there were no cooks available at the premier's official residence.

Netanyahu, prime minister for around 12 years in total and with no rival in sight, has maintained his innocence in all the cases.

But the investigations have gradually ratcheted up speculation over whether he will eventually be forced from office.

So far his coalition partners have stood by him despite the allegations. He is not obliged to step down as prime minister even if he is formally charged.