The Israeli Justice Ministry made the announcement in a terse message late on Thursday, saying the investigation would focus on a recent report by the Uvda investigative program into Sara Netanyahu.
The program uncovered a trove of WhatsApp messages in which Sara Netanyahu appears to instruct a former aide to organise protests against political opponents and to intimidate Hadas Klein, a key witness in the trial.
The prime minister described the allegations as "a merciless attack" on his wife, Sara. (AP PHOTO)
The announcement did not mention Sara Netanyahu by name and the Justice Ministry declined further comment.
But in a video released earlier on Thursday, Benjamin Netanyahu listed what he said were the many kind and charitable acts by his wife and blasted the Uvda report as "lies".
"My opponents on the left and in the media found a new-old target. They mercilessly attack my wife, Sara," he said. He called the program "false propaganda, nasty propaganda that brings up lies from the darkness".
It was the latest in a long line of legal troubles for the Netanyahus — highlighted by the prime minister's ongoing corruption trial.
Netanyahu is charged with fraud, breach of trust and accepting bribes in a series of cases alleging he exchanged favours with powerful media moguls and wealthy associates.
Netanyahu denies the charges and says he is the victim of a "witch hunt" by overzealous prosecutors, police and the media.
The report obtained correspondence between Sara Netanyahu and Hanni Bleiweiss, a former aide to the prime minister who died of cancer last year.
The messages indicated that Sara Netanyahu encouraged police to crack down violently on anti-government protesters and ordered Bleiweiss to organise protests against her husband's critics. She also told Bleiweiss to get activists in Netanyahu's Likud party to publish attacks on Klein.
Klein is an aide to billionaire Hollywood mogul Arnon Milchan and has testified in the corruption case about her role in delivering tens of thousands of dollars worth of champagne, cigars and gifts to Netanyahu for her boss.
According to the report, Sara Netanyahu mistreated Bleiweiss, prompting her to share the messages with a reporter shortly before her death.
Sara Netanyahu has been accused of abusive behaviour toward her personal staff before.
This, together with accusations of excessive spending and using public money for her own extravagant personal tastes, has earned her an image as being out of touch with everyday Israelis.
In 2019, she was fined for misusing state funds.
