Far right groups and messaging forums being used to organise the UK riots contain messages encouraging followers to attack Jews, community security experts have warned.

The Community Security Trust told the Guardian newspaper that a forum being used to instigate the first riot in Southport, is allegedly jointly run by a suspected neo-Nazi.

The individual, who experts believe to be based overseas, is alleged to have encouraged supporters to target synagogues and communal buildings.

CST said he was reported to the police last year for alleged encouragement of violent antisemitism.

One message in the forum insults “Gypsies” as well as Jews.

It comes as fears grow over calls from far-right organisers to target 30 sites around England on Wednesday, many are linked to immigration and asylum locations.

One of the locations allegedly set to be targeted is in Finchley, north London.

A CST spokesperson told the Guardian: “There are some people in this movement and their online spaces encouraging others to consider Jews as a target, as well as everyone else they have identified so far, such as ethnic minorities, Muslims and asylum seekers.”

The spokesperson said the CST has been supporting Jewish buildings near the planned protests and were “advising them about Wednesday night and about appropriate security measures.

“We can not ignore the potential it might affect the Jewish community.”

Security for synagogues, Jewish schools and community halls was already on high alert before the riots across the UK erupted.

Antisemitic incidents in the UK rose significantly immediately after the Hamas attack on Israel on October 7.

The number of antisemitic incidents recorded by CST from October 2023 to December was up to five times higher than over the same period the previous year.

CST said it was concerned that antisemitic content on far-right forums is linked to the violent disorder over the last week.

The CST spokesperson said: “We see this kind of antisemitic chat from the far right all the time in a variety of online forums. The difference is it is now in online spaces which are also being used by people who are going out and who are actually involved in violent disorder.”

CST has offered its support and cooperation to the charity Tell Mama which works to protect the Muslim community and combat anti-Islamic hatred.