Israeli Prime Minister Benjamin Netanyahu has been suspected of bribery, fraud and breach of trust by the police, according to local media reports.

An Israeli court, also on Thursday, said two police investigations in which Netanyahu has been questioned could result in corruption charges.

The revelations came during a court hearing in which it was disclosed that prosecutors are negotiating with a former senior aide to Netanyahu, the Haaretz newspaper said. 

They are said to be trying to obtain testimony from former chief of staff Ari Harow about two cases relating to gifts allegedly given to Netanyahu and his family by business figures and discussions he had with a newspaper publisher.

The disclosures, made in an court order limiting media coverage of the cases, did not name Netanyahu. But they ramped up speculation among Israeli legal analysts that he could face indictment if Harow turns state's witness.

Netanyahu has denied any wrongdoing, and his spokesman said in a statement on Thursday that the premier was the target of "a witch-hunt, now at its peak, aimed at changing the government".

"This is destined to fail, for a simple reason: Nothing will happen because nothing happened," the spokesman said.