Israel's Prime Minister Benjamin Netanyahu denied corruption charges during a court appearance, as his graft trial resumed on Monday, weeks ahead of a fourth national election within two years, reported news agency AFP.

Netanyahu was formally charged last year over allegations of accepting improper gifts and seeking to trade regulatory favour with media moguls in exchange for positive coverage.

He is the first Israeli premier to be indicted in office.

"I confirm the written answer submitted in my name," Israel's longest-serving premier said, after Jerusalem court judge Rivka Feldman Friedman asked his response to 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.

Netanyahu has repeatedly claimed that he is the victim of a witch-hunt.

The hearing continued in his absence for several hours. The three-judge panel later released a ruling saying they would examine that complaint before moving forward with the prosecution's case.

That could result in a delay that keeps Netanyahu out of court until after the March 23 election.