Israel's Prime Minister Benjamin Netanyahu is to be questioned as a suspect in a further case of alleged corruption and as a witness in another, Israeli media reported on Sunday.

The police, who have questioned the prime minister seven times since the beginning of 2017, in mid-February recommended the premier be indicted for graft, fraud and breach of trust in two other cases.

The cases have fuelled speculation he could be forced to step down or call an early election. The political opposition Zionist Union chief Avi Gabbay told Haaretz: “We are at the end of Netanyahu’s days. It will take a few more months, maybe a year, but he won’t be with us. We can be optimistic.”

The decision on whether or not to indict him now rests with the attorney general.

Public radio and television on Sunday reported he will be questioned on Friday as a suspect in alleged attempts to seek positive media coverage through favours to telecommunications giant Bezeq.

Netanyahu is scheduled to leave on Saturday for the United States, where he will speak at the AIPAC Policy Conference and meet with US President Donald Trump, Haaretz said on its website.

The Tragedy of Suspect Benjamin Netanyahu | Analysis https://t.co/D2C1pgKZwF — Haaretz.com (@haaretzcom) February 25, 2018

He will also face interrogation as a witness in suspected corruption around Israel's purchase of three submarines from German industrial giant ThyssenKrupp.

A police spokesperson could not immediately confirm the reports.

The Bezeq case involves the main shareholder of Israel's top communications group, Shaul Elovitch and his wife, as well as group CEO Stella Handler and four others who were arrested in mid-February.

According to press reports, investigators are focusing on allegations that Elovitch, Bezeq's controlling shareholder, gave Netanyahu positive coverage on his Walla! news site in exchange for policies benefiting the business.

Shlomo Filber, a Netanyahu ally for more than 20 years and former director general of the communications ministry, is expected to agree to turn state witness in exchange for avoiding jail, according to Israeli media reports confirmed by police.

Gag order in place

A gag order prevented publishing any details of the deal.

Filber is suspected of mediating between Netanyahu and Elovitch and promoting regulatory changes worth millions to Bezeq.

The police on Sunday also extended the custody of Eli Kamir, a communications adviser suspected of being involved in the Bezeq case.

Kamir is also suspected, alongside Nir Hefetz, a fellow former media adviser to the Netanyahu family, of offering a judge promotion in exchange for dropping a case against the premier's wife over alleged misuse of public funds.

The police have already recommended Netanyahu's indictment in two cases.

In one, he and family members are suspected of receiving $285,000 of luxury cigars, champagne and jewellery from wealthy personalities in exchange for financial or personal favours.

In the other case, investigators suspect the premier of trying to reach an agreement with the owner of Yediot Aharonot, a top Israeli daily newspaper, for more favourable coverage.