A teenager who allegedly stabbed an Orthodox Jewish man in Switzerland was radicalised in Tunisia and online, Zurich's regional security minister said on Monday.

Investigations into the March 2 attack are progressing at a swift pace, Mario Fehr said during a press briefing on cantonal crime statistics.

The 15-year-old suspect claimed responsibility for the attack in a video in Arabic in which he pledged allegiance to the Islamic State jihadist group and called for a "global fight against the Jews", police have said.

The boy is a Tunisian immigrant who was naturalised in Switzerland in 2011.

"There is a strong link with Tunisia", where the teenager spent four years between 2017 and 2021, Fehr said, according to Switzerland's Keystone-ATS news agency.

An important factor in his radicalisation was also the amount of time he spent on internet forums, said Fehr, who heads the Zurich cantonal administration.

The alleged perpetrator was arrested at the scene of the attack and is being held in custody.

The 50-year-old victim sustained serious injuries.

The Islamic State group claimed responsibility for Friday's gun attack at a Moscow concert hall which left at least 137 people dead.

In Switzerland, the number of anti-Semitic acts has reportedly increased significantly since October and the start of the conflict in Gaza.

Johanne Gurfinkiel, the secretary-general of Intercommunity Coordination Against Anti-Semitism and Defamation (CICAD), voiced surprise at the limited reaction to the Zurich attack.

"That such an event has not caused a national outcry is a real problem because it brings to light a lack of awareness of how serious the situation is," he told the Arc Info newspaper earlier this month.

Some 0.2 percent of people aged 15 or over in the Swiss population of 8.8 million. say their religion is Jewish, according to the latest government statistics.