Israel's Prime Minister Benjamin Netanyahu denied corruption charges against him in a brief court appearance Monday, as his graft trial resumed weeks before a fourth national election inside two years.

Netanyahu, the first Israeli premier to be indicted in office, was formally charged last year over allegations that he accepted improper gifts and sought to trade regulatory favour with media moguls in exchange for positive coverage.

He had been compelled to appear to deliver an in-person response to the charges, after last month formally submitting his innocent plea in writing.

Weekly protests against Netanyahu have rumbled on for months, with demonstrators from the 'Crime Minister' movement focusing on graft allegations the premier faces
Weekly protests against Netanyahu have rumbled on for months, with demonstrators from the 'Crime Minister' movement focusing on graft allegations the premier faces AFP / MENAHEM KAHANA

"I confirm the written answer submitted in my name," Israel's longest-serving premier said, after Jerusalem court judge Rivka Feldman Friedman read out the charges against him.

Netanyahu was referring to a January 18 court filing from his defence team which said "the prime minister denies all charges" in each of the three separate cases against him.

The combative 71-year-old premier, who has previously blasted the charges as "fabricated and ludicrous", spent just 20 minutes inside the courtroom on Monday, entering and exiting amid a heavy security deployment and dozens of protesters.

Israeli Prime Minister Benjamin Netanyahu may have to appear in court multiple times a week as his trial on corruption charges ramps up, while also campaigning ahead of Israel's fourth election in less than two years
Israeli Prime Minister Benjamin Netanyahu may have to appear in court multiple times a week as his trial on corruption charges ramps up, while also campaigning ahead of Israel's fourth election in less than two years AFP / Jack GUEZ

The hearing continued in his absence for several hours, with Netanyahu's lawyers Boaz Ben Zur and Amit Hadad accusing Israel's Attorney General Avichai Mandelblit -- a Netanyahu appointee -- of mishandling the case.

They argued that elements of the investigation into the premier were opened without required authorisations.

Repeatedly suggesting the charges against him have been trumped up, Netanyahu has taken direct aim at his hand-picked attorney general, Avichai Mandelblit
Repeatedly suggesting the charges against him have been trumped up, Netanyahu has taken direct aim at his hand-picked attorney general, Avichai Mandelblit AFP / Menahem KAHANA

Netanyahu has repeatedly charged that he is the victim of a witch-hunt, with the allegations against him trumped-up.

The trial schedule has not yet been set but it may force the prime minister to appear in court multiple times a week, as he campaigns ahead of Israel's March 23 elections.

Repeatedly suggesting the charges against him have been trumped up, Netanyahu has taken direct aim at his hand-picked attorney general, Avichai Mandelblit
Repeatedly suggesting the charges against him have been trumped up, Netanyahu has taken direct aim at his hand-picked attorney general, Avichai Mandelblit AFP / Menahem KAHANA

His lawyers asked for a delay of several months saying they needed more time to prepare due to the complexity of the case, but judges did not rule on that request before the hearing ended.

When Netanyahu last appeared in court nine months ago, he had just won a political victory by forming a coalition government with election rival Benny Gantz, following three inconclusive national polls.

But that fraught coalition proved short-lived and collapsed in December, with Gantz branding Netanyahu as serially dishonest.

Netanyahu may have to appear in court multiple times a week as his trial on corruption charges ramps up, while also campaigning ahead of Israel's fourth election in less than two years
Netanyahu may have to appear in court multiple times a week as his trial on corruption charges ramps up, while also campaigning ahead of Israel's fourth election in less than two years AFP / Jack GUEZ

It is unclear whether the cloud of the trial will hurt the premier's re-election chances in March.

Israel's parliament speaker Yariv Levin, loyalist of Netanyahu's right-wing Likud party, insisted the court must "postpone" the trial's upcoming phase.

Proceeding now "will be lending a hand to blatant meddling in the elections", he told the right-wing Israel Hayom newspaper on Sunday.

Several recent polls show that Netanyahu's right-wing Likud remains the strongest party by a comfortable margin, but it is far from certain that it will be able to form a 61-seat majority with its conservative and religious allies.

The charges against Netanyahu are divided into three separate cases.

The most serious -- known as Case 4,000, in which the premier is accused of bribery, fraud and breach of trust -- centres on the allegation that he negotiated with Shaul Elovitch of telecommunications giant Bezeq to secure positive coverage on his Walla! news site in exchange for policies benefiting Bezeq.

Elovitch and his wife were also indicted.

Case 2,000 concerns allegations Netanyahu sought a deal with the owner of the Yediot Aharonot newspaper that would have seen it give him more favourable coverage.

Case 1,000 involves allegations Netanyahu and his family received gifts, including luxury cigars, champagne and jewellery estimated to be worth more than 700,000 shekels ($213,000), from wealthy individuals, in exchange for financial or personal favours.

He would be forced to resign if convicted with all appeals exhausted, but that process would likely take several years.

Weekly protests against him have rumbled on for months, with some demonstrators focusing on the graft allegations.

Some of the protesters who met Netanyahu's motorcade outside the court carried placards branded with the words "Crime Minister", while other demonstrators taunted him as he entered and exited the court.

"We are here to swipe (away) all the dirt and all the corruption that he has created," protester Claudia Manoquian told AFP.