Israeli supermodel Bar Refaeli has been urged not to marry her non-Jewish boyfriend Leonardo Di Caprio by a group of strictly Orthodox Jews.

Extreme right-wing activist Baruch Marzel, the head of the Jewish National Front, wrote to Bar Refaeli on behalf of his group Lehava urging her not to “dilute the Jewish race.”

He told the supermodel, who has recently rekindled her romance with American actor Mr DiCaprio: “It is not by chance that you were born Jewish.

"Your grandmother and her grandmother did not dream that one of their descendants would one day remove the family's future generations from the Jewish people.

"Assimilation has forever been one of the enemies of the Jewish people."

He added that he "has nothing against Mr DiCaprio, who I have no doubt is a talented actor.

"Come to your senses, look forward and back too — and not only the present. Don't marry Leonardo DiCaprio, don't harm the future generations."

Lehava’s Facebook page claims one of its roles is to provide “assistance” to Jewish girls who are in relationships with non-Jews.

Mr Marzel has a record of violence in Israel, including assaults on a Palestinian, an Israeli police officer and Israeli left-wing journalist Uri Avnery. He has also declared a “holy war” against homosexuals in Israel..