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.