The justice ministry had not confirmed he would announce his decision on Thursday, but Israeli news media across-the-board were reporting it was imminent and television stations were broadcasting special coverage in anticipation.

The reports come with Netanyahu in the midst of a tough re-election campaign ahead of April 9 polls.

Under Israeli judicial procedures, Attorney General Avichai Mandelblit would announce whether he intends to indict Netanyahu pending a hearing, where the prime minister would be given an opportunity to defend himself before charges are filed.

Some reports said Mandelblit would move to indict the prime minister for bribery, which a Netanyahu spokesman said would be "ridiculous" and "absurd".

Netanyahu denies all allegations against him and calls the investigations a bid by his political enemies to force him from office.

His right-wing Likud party announced Thursday it had joined a petition filed with the supreme court to stop Mandelblit from announcing his decision before the elections, calling it a "blatant intervention" in the vote.

The supreme court on Thursday afternoon rejected the petition, and Likud called the decision "regrettable."

Netanyahu meanwhile received support from US President Donald Trump, who defended his Israeli ally in remarks after his summit in Hanoi with North Korean leader Kim Jong Un.

"I can say this, he's done a great job as prime minister," Trump said.

"He's tough, smart, and strong. He's very defensive, his military has been built up a lot."

Netanyahu later thanked Trump on Twitter.

The prime minister also posted an animated video in which a voiceover calls the investigations a "house of cards" and rebuts accusations against him.

Police have recommended Netanyahu's indictment in three different cases.

In one case, he is accused of pursuing regulatory benefits allegedly granted to telecommunications firm Bezeq in exchange for positive coverage from a related media company.

Another involves Netanyahu allegedly seeking a secret deal with the publisher of Israel's top-selling newspaper Yediot Aharonot to ensure positive coverage in return for pushing forward a law that would have limited the circulation of a rival.

The third case involves suspicions the premier and his family received luxury gifts from wealthy individuals in exchange for financial or personal favours.

The 69-year-old has been prime minister for a total of around 13 years and he would be on track to surpass founding father David Ben-Gurion as Israel's longest-serving premier should he win in April.

Netanyahu and his Likud party are facing a serious challenge from a centrist alliance led by respected former military chief of staff Benny Gantz.

The agreement to form the alliance under the name Blue and White -- the colours of the Israeli flag -- has shaken up the campaign.

Prior to the February 21 announcement of the alliance, Likud had consistently been comfortably ahead in opinion polls.

Polls since then have shown Gantz's alliance with the most seats, though not nearly enough to win outright and it is unclear if he would be able to assemble enough parties for a coalition.

lal-jjm-scw-mjs/dr