The Israeli-Palestinian conflict is again extending its reach onto University of California campuses, raising questions about the limits of free speech and how welcome Jewish and Muslim students feel at their schools.

But this time, the controversy does not spring from the kind of direct confrontation that occurred two years ago when Muslim protesters tried to shout down the Israeli ambassador during a speech at UC Irvine and then faced criminal prosecution. Instead, the current debate is being stirred by studies UC commissioned about how to cool tempers and whether anti-Semitism and anti-Muslim bias are serious problems on the system's 10 campuses.

The reports revealed that some Muslim students feel their rights are being suppressed and some Jewish students think anti-Israel protests on campus have become anti-Semitic.

UC commissioned the separate studies last year as part of a wider effort to improve relations in the wake of racially offensive incidents at UC San Diego and other cases of perceived bias around the system.

UC President Mark G. Yudof said he did not think there had been a significant increase in ethnic and religious friction on campuses, although the Internet era speeds up any traditional "intellectual debate." Passions are raised, he said, because ethnicity and religion are at "the essence of a human being and a culture and how people identify themselves in the world."

The advisory reports, issued in draft form this summer, found that Jewish and Muslim students were doing quite well but reported some ill ease and prejudice, especially around protests about the Israeli-Palestinian conflict and when Muslims students wore hijabs or other easily recognizable religious attire. Portions of both groups also said they wanted more accommodation for religious observances, such as preparing kosher and halal foods and providing late-evening meals for Muslim students who observe daytime fasting during the month of Ramadan.

The study that focused on Jewish students suggests that campus protests against the Israeli occupation of the West Bank sometimes take on such anti-Semitic overtones that they "engender a feeling of isolation, and undermine Jewish students' sense of belonging and engagement with outside communities." It contends that UC does not tolerate similar verbal attacks on other minority groups.

That report recommends that UC define hate speech and prohibit it on campus. It suggests that a description of anti-Semitism might include likening Israeli policies toward Palestinians to treatment of Jews by Nazis during the Holocaust. The document acknowledges that such rules might prompt legal challenges but urges UC to "accept the challenge."

The other study said that Muslim and Arab students thought their political activities were unfairly scrutinized in the post-9/11 era and that the harshness of the punishment in the UC Irvine incident had deepened discomfort and limited liberties. UC Irvine suspended the Muslim Student Union from campus activities for an academic quarter because of its role in the heckling of the Israeli ambassador. during his Feb. 2010 speech. The Orange County district attorney brought misdemeanor criminal charges against the Muslim students and 10 were convicted and sentenced to probation and community service, which they are appealing.

In addition, the report said that easily identifiable Muslims, such as those wearing religious garb, and politically active ones face "persistent insensitivity" among faculty, students, staff and police.

Yudof said that he would probably implement some recommendations in the reports, especially the ones about better accommodating religious observances. But in a recent interview, he said he wouldn't adopt any limits on speech since those would violate the 1st Amendment.

"In general, anti-Semitic, anti-Hispanic, anti-black, anti-women, anti-gay speech, as opposed to action or discrimination, is protected," Yudof said, adding that he would work to ensure that no student is illegally harassed and that no hate crime laws are broken.

Yudof said he would not bring the reports up to a formal vote when his Advisory Council on Campus Climate meets Oct. 22. That council was formed after an off-campus 2010 "Compton cookout" party at UC San Diego openly mocked African Americans and triggered protests there

Adding another layer to the debate, the state Assembly last month passed a nonbinding resolution urging UC to ban speakers who express anti-Semitism and call Israel a racist or Nazi state. The university did not endorse the resolution, saying it needed more protections for free speech. On Saturday , the UC Student Assn. leadership voted to protest that Assembly action and contended it could wrongly label critics of Israel as anti-Semitic.

Schools can ban incitement to violence and harassment but cannot prohibit political speech no matter how upsetting it may be, said Will Creeley, an official at the Philadelphia-based Foundation for Individual Rights in Education, an organization that has sued universities nationwide to halt censorship. "The answer to offensive speech is more speech, not censorship," he said.

Creeley added, however, that he thinks the heckling of the Israeli ambassador violated free speech rules. He said he did not take a position on whether the criminal charges were merited.

San Diego attorney Richard Barton, who is a co-author of the report on Jewish students, said he was not seeking to stifle criticism of Israel, nor contending that all anti-Israel protests constitute hate speech. But when Nazi swastikas are used or the Star of David is defaced in those protests, UC has a "responsibility to prevent the campus environment from being hostile to students," said Barton, who is the national education chairman of the Anti-Defamation League. Where to draw the lines between liberty and protection can be difficult, he said, but UC should try to at least "explore more fully where those lines are."

Many Muslim students think UC responded to pressure from outside political groups when it suspended the Muslim Student Union after the heckling incident, said Imam Jihad Turk, one of the authors of the report on Muslim and Arab students and a religious advisor at the Islamic Center of Southern California. Those students also think UC should have fought the district attorney's decision to prosecute the students, he said.

Most Muslim and Arab students at UC feel "completely at home" except for those who are overtly visible as Muslim with beards or head scarves, he said. "Anyone who stands out feels unwelcome," said Turk, who is also dean of an Islamic seminary affiliated with Claremont Lincoln University.

The UC reports also have set off debate within the Jewish community.

Tammi Rossman-Benjamin, a Hebrew language lecturer at UC Santa Cruz whose allegations of campus anti-Semitism set off a federal civil rights investigation, said the report on Jewish students accurately portrayed how anti-Israel protests make them feel under attack.

But Cecilie Surasky, an official at the Oakland-based Jewish Voice for Peace, a group that opposes Israel's occupation of the West Bank, said that the UC report seemed to exaggerate any anti-Semitism at UC and the hurt feelings of Jewish students. In fact, she said, Jewish students participate in protests against Israel's treatment of Palestinians. Any limits on free speech, she added, "are anathema to everything a university stands for."