The State Department has taken the groundbreaking step of identifying some virulent criticism of Israel as anti-Semitism, as it warns that anti-Jewish attitudes and incidents are on the rise worldwide.

In a new study, the department cites Tel Aviv University’s Stephen Roth Institute in reporting an increase of serious anti-Semitic incidents across the globe, encompassing physical attacks and vandalism, from 406 in 2005 to 593 in 2006.

The new study, “Contemporary Global Anti-Semitism,” also cites a range of other nongovernmental organizations to show dramatic increases in Latin America, Australasia and Europe, including a 31 percent spike in Britain from 2005 to 2006 and a 35 percent jump in Argentina during the same period.

The report goes quite far in warning about the intensification of anti-Semitic rhetoric among governments and international elites. Its policy recommendations are unusually strong for State Department reports, which generally refrain from pronounced language.

Its boldest venture is to name some attacks on Israel as anti-Semitism — a first for the U.S. government.

“Anti-Semitism has proven to be an adaptive phenomenon,” the report said. “New forms of anti-Semitism have evolved. They often incorporate elements of traditional anti-Semitism. However, the distinguishing feature of the new anti-Semitism is criticism of Zionism or Israeli policy that — whether intentionally or unintentionally — has the effect of promoting prejudice against all Jews by demonizing Israel and Israelis and attributing Israel’s perceived faults to its Jewish character.”

U.S. diplomats and other officials will be expected to take their cues from this forceful language in how they deal with political groups and individuals overseas.

In its introductory overview — generally the part of any report that is most closely read by U.S. officials seeking guidance on an issue — the report singles out governments that have had particularly parlous relations with the Bush administration, including Iran, Syria and Venezuela.

The body of the report, however, includes pronounced examples of anti-Semitism among the nations that the United States has cultivated as allies, including Russia, Ukraine and Iraq.

The report, which was sent to Congress last month, culminates four years of research launched in 2004 after U.S. lawmakers passed a bill commissioning it. The process was accelerated in 2006 when President Bush named Gregg Rickman the first U.S. special envoy on anti-Semitism.

Jewish groups, including the Anti-Defamation League and the American Jewish Committee, welcomed the report, as did some members of Congress.

“All too often, legitimate criticism of the state of Israel can veer into naked anti-Semitism characterized by vile hate speech,” said Rep. Howard Berman (D-Van Nuys), the chairman of the House of Representatives Foreign Affairs Committee. “When hate speech arises, we should call it what it is — and do what can be done to stop it.”

The 94-page report deals at length with Holocaust denial as a vehicle for anti-Semitism, focusing particularly on the role Iran’s government has taken in its propagation. It also targets the United Nations system, saying the double standards some of its constituent bodies display toward Israel promote a hostile environment for Jews.

“Regardless of the intent, disproportionate criticism of Israel as barbaric and unprincipled, and corresponding discriminatory measures adopted in the U.N. against Israel, have the effect of causing audiences to associate negative attributes with Jews in general, thus fueling anti-Semitism,” it says.