Jewish leaders have expressed concern over the falling number of prosecutions for hate crime in the UK last year, after the latest figures were revealed during Hate Crime Awareness Week.

Police said the number of hate crimes being recorded in the past year had in fact skyrocketed, rising 29 percent, partly in response to the aftermath of the Brexit debate and attacks by radical Islamists in Manchester and London Bridge.

However, while Home Office data showed almost 18,000 more hate crimes offences in the last 12 recorded months, the Board of Deputies said it was “concerned” that the number of successful prosecutions had fallen when anti-Semitism was rising.

The Crown Prosecution Service noted in its report there the number of hate crime cases being referred by the police were still around 13,000 per year, almost ten percent less than in 2014/15, leaving Jewish groups with concerns.

“All evidence points to a rise in anti-Semitic and other hate crimes,” said Board president Jonathan Arkush. “The Crown Prosecution Service says that there are less referrals from the police, and this needs to be investigated.”

He added: “If it is a question of police attitudes or resourcing, this needs to be urgently addressed. History shows us that where low-level abusive and discriminatory behaviours goes unchecked, much worse can follow.”

Dave Rich, a spokesman for the Community Security Trust (CST), said the increase in reported hate crime was “worrying,” adding: “It underlines CST’s figures showing anti-Semitic hate crime went up over the same period.”

However CST director Mark Gardner said that while “obviously we want to see an increase in the number of successful prosecutions, not a decrease… the proportion of cases leading to conviction remains the same, so there is more detail to this than first appears”.

The four spikes in racially or religiously aggravated offences in England and Wales in the last year were in June 2016, and in March, May and June of this year, coinciding with Britain voting to leave the EU, the Westminster Bridge attack, the Manchester Arena bombing and the attacks at Borough Market and Finsbury Park Mosque.

The data splits hate crime into offences motivated by race, religion, sexual orientation, disability or transgender identity, with racially-aggravated offences by far the most common, making up 78 percent of all reported cases.

Mustafa Field, a director of the Faiths Forum for London group which organised a vigil after the Westminster attack, said: “Perpetrators need to know that such offences will not be tolerated in our communities, and that they will be dealt with under the full force of the law.”

The Campaign Against Anti-Semitism (CAA) said that of the 14,480 hate crimes prosecuted by the CPS last year, a “paltry” number were for anti-Semitism. “We are yet to see a year in which the CPS has prosecuted more than two dozen hate crimes against Jews,” a CAA spokesman said.

Rabbi Herschel Gluck, president of Stamford Hill Shomrim, said: “I am very pleased that the Government is taking Hate Crime seriously, but there is still some way to go that sentencing should reflect the severity of the trauma suffered by its victims”