Swiss police arrested a teenager on suspicion of stabbing an Orthodox Jewish man in Zurich, leaving him critically injured.
Anti-Semitism is thought to have been the motive for the stabbing, which took place on Saturday evening, Zurich police said in a statement.
Rita Katz, director of the Site Intelligence Group, a counterterrorism group specialising in tracking global extremism, said the teenager, who identified himself as Ahmed Al Dabbah, had pledged allegiance to ISIS in a series of videos posted online.
Writing in a post on LinkedIn, Ms Katz said he had also threatened to launch a major attack on Jews in Switzerland and called on like-minded individuals to attack Jews not only in Palestinian territories, but across the world.
ISIS has not claimed responsibility for the attack or featured any of the videos via its Amaq News Agency, she added.
Police described the perpetrator as 15-year-old Swiss citizen, and said they arrested him at the scene.
They received a report of an argument involving several people and according to their initial findings, the perpetrator attacked the 50-year-old man “and critically injured him with a stabbing weapon”.
Police later issued a second statement saying they were increasing security around certain sites with Jewish connections as a precautionary measure. They said they made the decision in consultation with Jewish groups.
The Swiss Organisation of Jewish Communities said it was “deeply shocked that a community member fell victim to such an attack.”
“Physical attacks on Jewish people in Switzerland are very rare," it said.
"The Jewish community has been spared from such life-threatening attacks for the past two decades.
"However, there has been a significant increase in such physical attacks since October 7.”
French police search for assailant after man attacked leaving synagogue
Meanwhile, authorities in France are searching for an assailant who attacked a man leaving a synagogue in Paris, the country's Interior Minister Gerald Darmanin said late on Saturday.
Mr Darmanin said the alleged attack on Friday evening targeting a man in his early 60s was “a new anti-Semitic attack that occurred in Paris".
“Everything is being done to apprehend the perpetrator of this unspeakable act,” Mr Darmanin said in a post on X on Saturday evening.
A statement from the Paris public prosecutor's office said an assailant was seen physically and verbally assaulting a 62-year-old man who was wearing a Jewish skullcap as he was leaving a synagogue in the French capital’s 20th arrondissement on Friday at about 5.30pm local time.
A witness saw an assailant hit the victim, who fell on the ground and briefly lost consciousness, the prosecutor's office said in a statement emailed to the Associated Press.
A witness reported to the police that the assailant shouted an ethnic slur at the man under attack.
The victim was taken to hospital, the statement said, adding that the perpetrator fled on foot.
The attack came hours after Mr Darmanin said he had ordered police prefectures around the country to “immediately strengthen protections” of Jewish communities, particularly around schools and places of worship.
Mr Darmanin said in a post on X that surveillance had been heightened around places frequented by “our Jewish compatriots” to prevent them being targeted because of the “unfolding tragedies in the Middle East”.
There has been a rise in anti-Semitic acts across Europe since the start of the Israel-Gaza war, when Hamas-led militants stormed across southern Israel on October 7, killing about 1,200 people and taking about 250 hostage.
The number of Palestinians killed in the Gaza Strip since is more than 30,400.
