The head of Israel's prominent anti-settlement group Peace Now filed a police complaint on Tuesday after an anonymous caller left a message on his phone apparently threatening to kill him.
Yaariv Oppenheimer told AFP he filed the complaint with local police a day after receiving the voicemail message on Monday morning.
"We get threats sometimes," he said. "This time it sounded more serious."
"The guy called us and left a message saying he will make sure that I will not finish this year," Oppenheimer said.
Peace Now, which advocates against the Israeli occupation of the Palestinian territories and opposes settlement construction, has been the frequent target of right-wing activists angered by its work.
But Oppenheimer said the explicit and unabashed nature of the latest threat prompted him to file a complaint.
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"When someone is leaving a very clear statement saying that he will take care of ending my life this year, and when he is doing it with his phone number open, it wasn't a secret number, it seems much more disturbing," he said.
Oppenheimer said Peace Now has seen an increase in incidents targeting its offices and members in recent months, which he said appeared to be linked to its criticism of illegal settlement outposts in the West Bank.
The outposts, established without Israeli government permission, are illegal under Israeli law, and Peace Now has vocally pushed for them to be dismantled, including through the courts.
Their pressure has forced the government to consider ways to move or disband outposts, including Migron, the biggest and oldest in the West Bank.
In early November, attackers scrawled abusive graffiti and death threats on the building that is home to another prominent Peace Now activist, Hagit Ofran.
The attack was the second targeting Ofran, and came a a day after Peace Now's offices were daubed with similar graffiti and subjected to a bomb hoax.
Oppenheimer said the group had taken security measures, which he declined to detail, since the attacks.