Israel's Prime Minister Benjamin Netanyahu on Wednesday slammed what he called a "left-wing and media campaign" aimed at overthrowing him as he faces ongoing investigations.

"The media has mobilised in an obsessive campaign against my family and me, but you the voters are the ones really targeted," he said to applause at a rally of his right-wing Likud party in Tel Aviv.

Organisers said more than 3,000 people gathered in support of the premier.

The rally came after officials last week said Netanyahu's former chief of staff, who has been investigated in graft cases involving the premier, had agreed to turn state witness.

According to reports, Ari Harow has already been supplying investigators with information regarding two of the ongoing investigations.

One is based on suspicions that Netanyahu unlawfully received gifts from wealthy supporters, including Australian billionaire James Packer and Hollywood producer Arnon Milchan.

Also being probed are allegation that he sought a secret deal with the publisher of top-selling daily Yediot Aharonot.

The deal, not believed to have been finalised, would reportedly have seen Netanyahu receive positive coverage in return for helping scale down the operations of Israel Hayom, Yediot's main competitor.

Netanyahu has been questioned on both cases.

The investigations have stirred speculation that Netanyahu may be forced to step down.

The premier has rejected allegations of misconduct in all the affairs, saying repeatedly that he is the target of a campaign by political opponents.

"The people are with us," Netanyahu said at Wednesday's rally, accompanied by his wife Sara, who has also been grilled on suspicion that she diverted public money for private housekeeping expenses.

Source: AFP