LOS ANGELES (Reuters) - Anti-Semitic assaults rose dramatically in the United States last year to 56, and the overall number of hateful incidents targeting Jews increased by 3 percent, the Anti-Defamation League said in a report on Wednesday.

Colleges in particular have become a place where Jews are particularly exposed to harassment, with anti-Semitic incidents at university campuses accounting for 10 percent of occurrences nationwide, the league said.

“We are disturbed that violent anti-Semitic incidents are rising,” Jonathan Greenblatt, chief executive of the Anti-Defamation League, said in a statement.

The 56 anti-Semitic assaults nationwide in 2015 represented an increase of more than 50 percent from the year before, according to the ADL.

The group said it was not clear what may have led to the spike.

Overall, the ADL report said, the United States had 941 anti-Semitic incidents in 2015, which aside from assaults included harassment, threats and vandalism.

The figures, which the group said may not include incidents that were not reported by victims, are based on reports collected by the ADL at its regional offices and data from law enforcement agencies.

Anti-Semitism on U.S. college campuses has concerned many in the Jewish community, and it has occurred as on-campus activists have led heated anti-Israel protests and calls to boycott and divest from the Middle East country in a movement they call anti-Zionism.

The University of California’s regents declared in March that they would not tolerate anti-Semitism on campus but rejected a proposal to equate anti-Zionism with religious bigotry, as they tried to defuse tensions between pro-Israeli and pro-Palestinian students.

Attacks on Jews have long accounted for a significant share of hate crimes in the United States.

The FBI, in its latest hate crime statistics released in November, said that in 2014 more than 56 percent of the anti-religious hate crimes in the United States that year were motivated by anti-Jewish bias.

More than 16 percent of anti-religious hate crimes targeted Muslims, according to the FBI.