Israeli Prime Minister Benjamin Netanyahu has arrived at a Tel Aviv courthouse to take the stand for the first time in a long-running corruption trial.

A few dozen protesters gathered outside during his arrival at around 10am local time, some of them supporters and others demanding he do more to negotiate the release of hostages still held by Hamas in Gaza.

The Israeli prime minister has denied any wrongdoing and has pleaded not guilty to the charges of bribery, fraud and breach of public trust in three separate cases.

He was indicted in 2019 over three cases involving gifts from millionaire friends and for allegedly seeking regulatory favours for media tycoons in return for favourable coverage.

Mr Netanyahu is Israel's longest-serving leader and its first sitting prime minister to be charged with a crime.

Before Mr Netanyahu took the stand, his lawyer Amit Hadad laid out for the judges what the defence maintains are fundamental flaws in the investigation.

Mr Hadad said prosecutors "weren't investigating a crime, they were going after a person."

Mr Netanyahu told the packed court he had waited eight years for this moment to say the truth.

He said the charges against him were "an ocean of absurdness" and promised his version would cut through the prosecution's case.

"Had I wanted good coverage all I would have had to have done would be to signal toward a two-state solution... had I moved two steps to the left I would have been hailed," Mr Netanyahu told the court.

Mr Netanyahu had been granted a delay for the start of his court appearances, but last week judges ruled that he must start testifying.

The court said he will testify three times in a week, despite the war in Gaza and possible new threats posed by wider tensions in the Middle East, including in neighbouring Syria.

In the run-up to his court date, he revived familiar pre-war rhetoric against law enforcement, describing investigations against him as a witch hunt.

"The real threat to democracy in Israel is not posed by the public's elected representatives, but by some among the law enforcement authorities who refuse to accept the voters' choice and are trying to carry out a coup with rabid political investigations that are unacceptable in any democracy," he said in a statement on Thursday.

The Israeli leader on Monday said he had waited eight years to be able to tell his story and expressed outrage at the way witnesses had been treated during investigations.

His domestic legal woes were compounded last month when the International Criminal Court (ICC) issued an arrest warrant for him and his former defence chief Yoav Gallant along with a Hamas leader, for alleged war crimes in the Gaza conflict.

The trial is scheduled to last for several months.

Wires