Israeli Prime Minister Benjamin Netanyahu is suspected of bribery and other charges in two cases, police confirmed on Thursday — and a spokesman slammed the "unfounded claims," vowing that any effort to change the government was "destined to fail."

Israel Police confirmed the charges, which also included fraud and breach of trust, during a hearing in Israel Supreme Court, Haaretz reports.

Authorities disclosed the information as it sought a gag order in trying to obtain the cooperation of Netanyahu's former chief of staff in its investigation.

For his assistance, the former aide, Ari Harow, "would receive immunity from prosecution for alleged crimes involving his own government relations firm," Haaretz reports.

The gag order is effective through Sept. 17.

"We completely reject the unfounded claims made against the prime minister," a Netanyahu representative told Haaretz in a statement.

"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."

Netanyahu, 67, who was elected to a fourth term in 2015, has been under investigation for allegedly receiving gifts from wealthy supporters.

They include Australian billionaire James Packer and Hollywood producer Arnon Milchan.

Also being probed are accusations that the prime minister sought a secret deal with the publisher of Yediot Aharonot, Israel's top-selling newspaper.

The alleged agreement would have given Netanyahu favorable coverage from Yediot in exchange for working to reduce the operations of its main competitor, Israel Hayom.

Authorities do not believe the alleged deal was made final, Haaretz reports.

Harow, the former head of the American Friends of Likud, has been under investigation for more than two years for trying to advance his firm while working in Netanyahu's office, The Jerusalem Post reports.

He was required to sell his firm, 3H Global, because of a possible conflict of interest.

Harow is suspected of bribery, breach of trust, conflict of interest and fraud, the Post reports.

According to Haaretz, Attorney General Avichai Mendelblit told the court that "we're making progress" in the case and that prosecutors were "working with the police" in obtaining Harow's cooperation.

"Let us work in peace and find the truth," Mendelblit later told reporters.

While the investigation has raised speculation on whether Netanyahu will eventually be forced to step down, Justice Minister Ayelet Shaked said he would not legally be required to if indicted.

"At the moment there is no charge against him and there is no recommendation to charge him," Shaked told news site Ynet on Wednesday.

"The ones to take that decision are the attorney general and the state prosecutor," she added.

"For now, let the prime minister get on with his job."

AFP contributed to this report.