The 17-year-old was wearing a yarmulka when he was attacked in Paris's multi-ethnic 19th district Saturday evening, according to Ariel Goldmann, vice president of the Representative Council of Jewish Institutions in France.
President Nicolas Sarkozy, who was traveling to Israel for a state visit, issued a statement expressing his "profound indignation" and reaffirmed his "total determination to combat all forms of racism and anti-Semitism."
Paris hospital officials said the teenager was in critical condition in intensive care. "There is no doubt that this is an anti-Semitic act," said Goldmann, who said the teenager was in a coma. "I call on authorities to do everything possible to arrest those responsible," he said.
Police said they had detained five youths in connection with the beating.Sammy Gholzan, from the Bureau for Vigilance on Anti-Semitism, said a group of six or seven youths attacked the teenager with metal bars and "smashed his skull."He said the young man was a member of the local Lubavitch community.
Interior Minister Michele Alliot-Marie said she was "deeply affected" by the attack and ordered investigators to spare no effort to find the perpetrators and shed light on the circumstances surrounding the violence.
She "expressed solidarity and support for the victim, his family and to the entire Jewish community, and reaffirmed her determination to fight tirelessly against all forms of racism, anti-Semitism and xenophobia, which flouts the values of the republic," said an interior ministry statement.
Anti-Semitism is a sensitive issue in France, where the 600,000-strong Jewish community is western Europe's largest, and which is also home to a five-million strong Muslim population.