TORONTO — The number of anti-Semitic incidents remained high in Canada in 2005, according to a new study, continuing a deterioration that began after the Sept. 11, 2001 terrorist attacks.

There were 829 anti-Semitic incidents reported in Canada in 2005, a slight decline from the peak of 857 in 2004, according to the annual audit of anti-Semitic incidents released this week by B’nai Brith Canada.

There has been almost a threefold increase in the number of anti-Semitic incidents reported since 2001, said Ruth Klein, national director of B’nai Brith’s League for Human Rights and one of the lead authors of the 60-page report.

“It’s like with 9/11, the genie was let out of the bottle, ” she said. “All of the polite prejudices that were just under the surface, they’ve now become much more evident. “

Of the incidents in 2005, 531 were classified as harassment, 273 as vandalism and 25 as violence.

Reports of anti-Semitic activities came from every province in Canada, though activity was mainly concentrated in the Greater Toronto and Greater Montreal areas.

There were 35 incidents reported against synagogues, 19 against Jewish communal buildings and 113 against private homes.

Public schools and universities were not immune, with 48 incidents each. Another 46 occurred in the workplace.

Internet hate was a particular focus of the audit, which recorded 161 such incidents, including 34 cases involving hate messages sent by e-mail. B’nai Brith officials speak of an “explosion ” of Internet hate.

“Today, more people are exposed on a daily basis to anti-Semitic literature and stereotyping of Jews than they were in 1939, ” at the height of Nazi Party propagandizing, said Frank Dimant, B’nai Brith Canada’s national executive vice president.

The audit identifies individuals of apparent Arab origin as being the largest single number of perpetrators, with 56 incidents.

Since only 10 percent of anti-Semitic incidents are reported, the latest figures represent only the tip of the iceberg, Dimant asserted. Most employees facing workplace discrimination or students enduring anti-Semitic remarks from their professors keep quiet for fear of losing their jobs or jeopardizing their grades, he said.

The survey is widely reported by Canadian news media and is regularly cited in U.S. State Department reports. It “is certainly the best known survey of its kind in Canada, ” said Harvey Goldberg, the team leader of strategic initiatives at the Canadian Human Rights Commission in Ottawa.

The 2005 survey is “particularly useful to us,” he said, because of its data regarding Internet hate, a key focus of the commission’s work.

B’nai Brith recommendations to ameliorate the situation include more consistent courtroom sentencing for hate crimes across Canada, the definition of Holocaust denial as a hate crime, criminalization of racist groups and the display of racist symbols, and stronger legislation against Internet hate.