Israel Prime Minister Benjamin Netanyahu is suspected of offences including bribery, fraud and breach of trust, Israeli police said.
In a document filed with a magistrate's court, the police on Thursday confirmed for the first time that Netanyahu is a suspect in two corruption cases which are under investigation, Xinhua news agency reported.
According to local media, Netanyahu is suspected of receiving bribes from Israeli-American Hollywood billionaire Arnon Milchan, and offering commercial favors to a newspaper publisher in return for positive coverage.
Police have issued a gag order as they try to persuade Netanyahu's former chief of staff Ari Harow to be a state witness in the cases. The court granted the order, which will remain effective until September 17.
A spokesman for Netanyahu rejected the claims as false and politically-motivated, according to Walla news site.
"We reject outright the unfounded claims," the spokesman said. "The campaign to replace the government is in full swing, but it is destined to fail, for a simple reason: there won't be anything because there was nothing."
Earlier on Thursday, Israel's Attorney General Avichai Mendelblit said talks with Harow were "making progress."
Netanyahu, 67, is a suspect in two cases. One, dubbed by the police as "Case 2000", involves secret talks he held with the owner of a large Israeli newspaper called Yediot Aharono about reducing the competition in the news sector in return for more positive coverage.
The other case, known as "Case 1000", involves suspicions that Netanyahu and his wife Sara received expensive gifts from Israeli-US businessman and Hollywood producer Arnon Milchan.
Netanyahu had been investigated by the police at least four times. In March, Police Chief Roni Alsheikh estimated the police are close to completing the investigation, saying "we are in the final stages".
The procrastination of the law enforcement authorities sparked anger in the Israeli public, leading to weekly demonstrations near the home of Mendelblit to demand charges against Netanyahu.