The study identified "young, disaffected white Europeans" as the largest group of culprits, followed by "young Muslims of North African or Asian extraction."
Traditionally, it said, anti-Semitic groups on the extreme right "play a part in stirring opinion."
Anti-Jewish incidents ranging from hate mail to arson are catalogued by the European Monitoring Centre on Racism and Xenophobia (EUMC) in the largest inquiry into the problem in Europe.
The EU body also emphasises that in many member states there is little evidence of any increase in anti-Semitism - in Ireland, Luxembourg, Portugal and Finland, there was "very little reported evidence of anti-Semitic incidents of any kind".
EUMC director Beatte Winkler said: "It is clear that anti-Semitism manifests itself with greater strength in some countries than in others, and where relatively reliable statistics are kept, there is evidence of an increase in the regularity of these incidents over the past two or three years.
"Such a conclusion is reached in the case of Belgium, Germany, France, the Netherlands and the UK."
The report urges EU governments to cooperate more closely in the fight against such racism - and suggests that school textbooks should be checked for bias, and teachers trained to raise awareness of cultural and religious differences and tradition in the EU.
The 344-page report, Manifestations of Antisemitism in the EU 2002 - 2003, is based on data collected by the EUMC's European information network, RAXEN, which has 15 offices in each member state.
Information was collected according to common guidelines in all countries and validated by an independent academic.
An accompanying 48-page report by the EUMC, based on interviews with the members of the Jewish community - reveals concerns about a more hostile environment in Europe.
The EUMC says: "Most Jewish people wish to be a recognised equal part of European societies and to live in good relationships with their neighbours."
On the five countries where the evidence shows increased anti-Semitic activity, the main report says:
UK - statistics "suggest that there has been a recent increase in both physical and verbal attacks against Jews."
Figures show a total of 350 reported anti-Semitic incidents in 2002, a 13% rise from the previous year.
Statistics for the first quarter of 2003 already show a 75% increase in incidents compared to the same quarter of 2002. In 2002 there were violent attacks on two synagogues, and in 2003 there were two cases of suspected arson and several attacks on Jewish cemeteries.
Belgium - there was a "catalogue of incidents of varying extremity" during the two-year research period, including the fire-bombing of Jewish property and some serious physical assaults, as well as many other incidents of insults, graffiti, hate speech and vandalism. The 64 acts recorded by one NGO in 2002 represent roughly double those it recorded in the two previous years.
Germany - anti-Semitism acts increased "considerably" (by 69%) from 1999 - 2000, and then increased slightly in 2001. In 2002 anti-Semitic violent crime rose to 28 incidents, compered with 18 in 2001.
But most incidents involved incitement and propaganda. Over the research period Jewish organisations in Germany reported big increases in aggressive anti-Semitic letters, emails and phone calls.
France - a "significant" rise in anti-Semitic violent incidents and threats in 2002 - six times as many as in 2001. Of 313 racist, xenophobic or anti-Semitic reported incidents 193 were anti-Semitic. There were "many incidents of Jewish people assaulted and insulted, attacks against synagogues, cemeteries and other Jewish property, and arson against a Jewish school."
The Netherlands - anti-Semitic incidents, ranging from targeted graffiti and threats to arson and assault, significantly increased in 2002, especially in Amsterdam, which has a relatively large Jewish community.
A worrying trend is the increasing dissemination of anti-Semitic material on Internet sites that are hosted in third countries.
At the other end of the scale, the report found that violent anti-Semitism was rare in Greece, Austria, Italy and Spain, although "extremely nasty anti-Semitic discourse" was "particularly virulent in many aspects of daily life."
In Ireland, Luxembourg, Portugal and Finland there was very little reported evidence of anti-Semitic incidents of any kind: "In Ireland there were a few incidents of abusive letters and phone calls with some further instances of anti-Semitic literature in leaflets or on websites."
In Luxembourg, representatives of the Jewish community, politicians, NGOs and experts "were unanimous in claiming that since the end of World War II Luxembourg has been free of anti-Semitic phenomenon."
On the culprits, the EUMC says: "In Belgium, Denmark, France, Germany, the Netherlands, Sweden, the UK, Italy and Austria, one broad group regularly referred to as perpetrators covers activists from the extreme right, and young white men influenced by extreme right ideas, including skinhead groups.
"Secondly, with the exception of Italy and Austria, victims in these countries often classified perpetrators to be 'young Muslims', 'people of North African origin', or 'immigrants'."
The report adds: "In general, on the basis of available data and looking at the EU as a whole, it is problematic to make general statements with regard to the perpetrators of anti-Semitic acts.
"In some countries the data collection is reasonably reliable, in some countries the bulk of the evidence is from the perceptions of victims, which are difficult to verify, and in other countries there is no evidence at all. This underlines the need for better official mechanisms for the recording of incidents."
At the report's Strasbourg launch, European Parliament President Pat Cox said: "The EUMC is to be congratulated for doing the first comprehensive and wide ranging study of this difficult and sensitive issue. This report gives Europe the foundation on which to build workable policies to counter anti-Semitism."
"The aim of this report," said Ms Winkler, "is to provide accurate data and information which can start a debate in Europe on how to counter anti-Semitism, and lead to effective policies across the Union.
"There are many examples of good practice and effective legislation in a number of member states which if implemented across the union could tackle the problem."
She added: "It is the greatest achievement of the European Union that conflict between member states is now inconceivable. It would be an even greater achievement if conflict between sections of the European community could also become inconceivable.
"Mutual respect for each other's human rights must be the basis of this."
The Vienna-based EUMC was set up in 19.