(JTA) — Haredi Orthodox Jews will soon account for half of the British Jewish population, according to a study of the kingdom’s Jewish communities.

Accelerating birth rates among the strictly observant religious Jewish communities mean they are expected “to constitute a majority of the British Jewish population before the 21st century is over,” a report from the Institute for Jewish Policy Research says, The Independent reported Thursday.

If high haredi birth rates continue, half of all Jewish children and around 30 percent of young Jewish adults living in the United Kingdom will be haredi by 2031, the report, which was published Thursday, says.

The report says Orthodox Jewish leaders should take note of the population boom. “The demographic dynamic of this community is conducive to the outbreak of social unrest,” it states, warning of an urgent need for job opportunities. Without these, “the probability [is] that youth will engage in antisocial activities, experience high levels of disillusionment, or abandon the strictly Orthodox lifestyle altogether.”

The report’s authors, Daniel Staetsky and Jonathan Boyd, warn that the haredi community should incorporate “sound employment and professional training opportunities” into the strictly Orthodox lifestyle “for its very preservation”.

The Orthodox charity Interlink Foundation said the report was flawed and understated the size of the haredi community, according to a report in The Jewish Chronicle. Its findings confirm that while mainstream Judaism in Britain is in decline, the haredi community is expanding.

Using 2011 census data and other surveys, the report’s authors say the Orthodox community is increasing by nearly 5 percent a year while the wider, non-haredi Jewish population is decreasing by 0.3 percent. Haredi birth rates are six to seven children per couple, more than three times the average UK national rate.