The arrest of two Green Party candidates over anti-Semitism allegations is “just the tip of the iceberg”, opponents have claimed. Saiqa Ali and Sabine Mairey, who are both standing for the party in central London, were detained by Met Police officers on Thursday morning. But The Telegraph can reveal almost 20 Green candidates at next week’s local elections have posted offensive material, with anti-Israel sentiment running deep in the party under Zack Polanski, its leader. They include one who referred to Jewish people as “cockroaches”, while others expressed support for Palestine Action, a banned terror group. Kevin Hollinrake, the Tory chairman, said: “These arrests appear to be just the tip of the iceberg when it comes to anti-Semitism in the Green Party. “Zack Polanski needs to step up and start taking action against those in his party who are openly promoting the oldest form of racism: anti-Semitism.” A Green Party spokesman said: “We are investigating anything brought to our attention that doesn’t fit with Green Party values and views.” Mothin Ali, the party’s deputy leader, …