TEL AVIV — An Israeli watchdog group has found a network of hundreds of social media accounts, many of them fake, used to smear opponents of Prime Minister Benjamin Netanyahu in next week’s election and to amplify the messages of his Likud party, according to a report to be released Monday.
The messages posted on the network’s Twitter and Facebook accounts are frequently reposted by prominent Likud campaign officials and by the prime minister’s son, Yair Netanyahu, the report says.
The watchdog group, the Big Bots Project, an independent organization that aims to expose the malicious use of social media, found no direct links between the network and Mr. Netanyahu, his party or his son, but said it appeared to operate in coordination with the party and Mr. Netanyahu’s re-election campaign.
“The network operates through manipulations, slander, lies and spreading rumors,” the report said. “On its busiest days, the network sends out thousands of tweets a day.”
The network’s activity has intensified almost fivefold since the election was called in December, the report said, and “is mobilized at climactic moments for Netanyahu, such as the announcement of the indictment against him.”
The report says the network may violate Israeli laws pertaining to elections, campaign finance, privacy and taxation.
A spokesman for the Likud party said that it did not run a network of fake accounts. “All of the Likud’s digital activity is entirely authentic and is based on the great support of the citizens of Israel for Prime Minister Netanyahu and the great achievements of the Likud,” the spokesman, Jonathan Urich, said on Sunday.
Mr. Netanyahu, who is facing an indictment on corruption charges, is in a tight race for what he hopes will be his fourth consecutive term. He is facing a strong challenge from Benny Gantz, a retired army chief, in the April 9 election.
According to the report, 154 of the accounts in the network use fake names and another 400 accounts are suspected of being fake. The accounts appear to be operated by people, not bots, making them much harder to detect, the report says. Their posts, all in Hebrew, have had over 2.5 million hits, the report’s authors estimate, in a country with 8.7 million citizens.
The report was written by Noam Rotem and Yuval Adam, founders of the Big Bots Project. They were assisted by the Israeli Alliance, a liberal-leaning organization, and their investigation was financed through an Israeli online crowdfunding site, Drove.
The New York Times and the Israeli newspaper Yediot Ahronot received advance copies of the report.
One of the accounts is under the name “Moshe,” whose handsome profile picture actually belongs to the Greek model Theo Theodoridis. Moshe, whose posts praise Mr. Netanyahu and excoriate his rivals, tweeted only 16 times during the first three months of 2018. By contrast, during the first three months of this year, with the election campaign underway, he tweeted 2,856 times.
The members of the network work in sync with each other, the report says. When one posted the false rumor that Mr. Gantz was a rapist, many of the others reposted it. On Thursday, many of the members almost simultaneously began tweeting that Mr. Gantz was mentally ill, echoing a video clip distributed by the Likud campaign.
As Mr. Gantz became Mr. Netanyahu’s chief rival, the network focused more on him. The network’s activity has often spiked at times of key political events.
The evening before the attorney general announced his decision to indict Mr. Netanyahu, the network circulated a Facebook post by an American woman saying that Mr. Gantz had sexually harassed her when they were in high school.
Mr. Gantz denied the accusation, and no support for it has been forthcoming, but the fabricated accounts pushed the story with tweets like: “Gantz the rapist to jail” and “Lousy scum rapist.”
Items posted by the network have also described Mr. Gantz, somewhat incongruously, as being gay and having a mistress.
The network has also attacked the attorney general, Avichai Mandelblit, echoing Mr. Netanyahu’s assertion that by seeking to indict the prime minister the attorney general had “surrendered to the media and the left.”
All accounts in the network are linked to that of a real person, Yitzhak Haddad, a resident of Ashdod.
The report cites a YouTube channel to which Mr. Haddad is an active subscriber, which has a message offering workers cash in exchange for “responding on Facebook and on the internet with political messages.”
“You just get political messages and you post them,” the message said.
It was not clear if the message was linked to the fake social network or whether Mr. Haddad ran the network.
When asked about the network on Sunday, Mr. Haddad said it was “all lies.”
He declined to confirm or deny that he was the person behind the Twitter account bearing his picture and email address, his connections with Likud, or his relationship to the YouTube channel recruiting workers for the election campaign.
In a later text message, Mr. Haddad wrote: “There is absolutely nothing in this. Anyone publishing this nonsense can expect a very large lawsuit.”
“You have no right to gag people on the right or on the left, period,” he added, “and the organization that is busy identifying accounts, who are they at all to decide for the open and free world?”
Mr. Urich, the Likud party spokesman, said that he did not know Mr. Haddad, and that Mr. Haddad was not employed by the Likud party and had no connection with Likud.
The network’s messages have been redistributed by prominent figures in the Likud campaign team. Yair Netanyahu, an unofficial adviser to his father’s campaign, has retweeted the network’s members 154 times, the report said. Similarly, the network “liked” and replied to his messages 1,481 times, and shared his messages 429 times.
Yair Netanyahu did not reply to a request for comment. Mr. Urich, speaking on his behalf, said, “Yair Netanyahu has no role in the Likud campaign, does not know the people of the network and is not involved in its activities, if any.”
Some of the tweets that include curse words and anti-Arab slurs are written using numbers that look like letters in the Hebrew alphabet, apparently so that a Twitter audit would not identify them as inappropriate and shut down the account.
There have been efforts to update Israeli election law to cover relatively recent developments in social media. After the work of a special panel headed by a former Supreme Court chief justice, Dorit Beinisch, an amendment to the law was proposed to cover social media.
The Likud party opposed the amendment and it did not pass.
Karine Nahon, president of the Israel Internet Association, who was a member of the Beinish panel, said: “We made a great effort to submit the recommendations as soon as possible so that legislation could already be enacted in the coming elections. But when a first reading bill was about to be voted on, the Likud decided in the middle of the night to remove it from the agenda.”