Israeli police confirmed on Thursday that Prime Minister Benjamin Netanyahu is suspected of bribery, fraud and breach of trust in two of its investigations.
The revelations came during a court hearing in which it was disclosed that prosecutors were negotiating with a former senior aide to Netanyahu, Haaretz newspaper reported.
The aide, Ari Harow, has agreed to give evidence against him about two cases relating to gifts allegedly given to Netanyahu and his family by business figures and discussions he had with a newspaper publisher.
"Prime Minister Benjamin Netanyahu's former chief of staff Ari Harow has reached an agreement with the prosecution to turn state's witness in two corruption cases against Netanyahu," Haaretz newspaper reported on its website.
"Former chief of staff Ari Harow signed today a state's witness agreement," public radio said.
Information the attorney general provided allegedly indicated criminal connections between Harow, Netanyahu and people in the PM's circles, according to Haaretz.
There was no official comment on the reports and any leaked details of the case are banned from publication by court order.
Harow has been under investigation for more than two years on suspicion of bribery, breach of trust, conflict of interest and fraud, the media said.
Two investigations against Netanyahu
Haaretz said Harow, who served as Netanyahu's chief of staff before resigning amid allegations of impropriety in 2015, has already been giving investigators information on two of the ongoing investigations into the PM.
Harow's decision to turn state's witness adds a further dimension to a long-running investigation involving Netanyahu, and increases the chances of the PM facing charges.
Although he would not be forced to resign if indicted, it would increase pressure on him to step down after 11 years in office.
One investigation, known as Case 1,000, involves Hollywood producer Arnon Milchan, who was allegedly asked to purchase luxury items for Netanyahu and his wife.
Netanyahu's wife Sara, was questioned by police on Wednesday.
She is accused of receiving "lavish and inappropriate" gifts from wealthy businessmen and paying bribes to a media mogul in return for favourable coverage.
Police have also launched a separate fraud investigation following accusations that Mrs Netanyahu had dipped into state funds to make personal expenditures.
Case 2,000 relates to claims of a proposed deal for more favourable coverage with Arnon Mozes, the publisher of Yedioth Ahronoth newspaper.
The details of the inquiries were included in a document submitted to Rishon Lezion Magistrate's Court, which ordered a media gag on the details of prosecutors' negotiations with Harow.
The order said the cases related to the "suspicion of the commission of the felonies of bribery, fraud and breach of trust."
Neither Harow nor his lawyer responded to requests for comment. Netanyahu has denied wrongdoing in both cases.
In a statement, his office said, "The campaign to change the government is underway, but it is destined to fail, for a simple reason: there won't be anything because there was nothing."