Waving a Palestinian flag or singing a chant advocating freedom for Arabs in the region may be a criminal offence, Suella Braverman has told senior police officers. In a letter to chief constables in England and Wales, the home secretary urged them to clamp down on any attempts to use flags, songs or swastikas to harass or intimidate members of the Jewish community. Her words, which follow deadly attacks by Hamas on Israelis and a military response, will deeply concern freedom of speech advocates and members of the Muslim community. In the letter, Braverman said police should not restrict themselves to potential offences related to the promotion of Hamas, a proscribed organisation. “It is not just explicit pro-Hamas symbols and chants that are cause for concern. I would encourage police to consider whether chants such as: ‘From the river to the sea, Palestine will be free’ should be understood as an expression of a violent desire to see Israel erased from the world, and whether its use in certain contexts may amount to a racially aggravated section 5 public order offence. “I would encourage police to give similar consideration to the presence of symbols such as swastikas at anti-Israel demonstrations. Context is crucial. Behaviours that are legitimate in some circumstances, for example the waving of a Palestinian flag, may not be legitimate such as when intended to glorify acts of terrorism. “Nor is it acceptable to drive through Jewish neighbourhoods, or single out Jewish members of the public, to aggressively chant or wave pro-Palestinian symbols at. Where harassment is identified, I would encourage the police to take swift and appropriate enforcement action. “I encourage all chief officers to ensure that any protests which could exacerbate community tensions by way of offensive placards, chants, or behaviours that could be construed as incitement or harassment, have a strong police presence to ensure perpetrators are appropriately dealt with, and that communities feel protected,” she wrote. Home Office sources confirmed her words had been approved by government lawyers. Decisions on arrests are an operational matter for the police, Braverman wrote. “However, I would urge you to ensure your forces use all available powers to prevent disorder and distress to our communities, and that your officers will act if there are any incidents that stray into criminality,” she said. The human rights barrister Shami Chakrabarti said “[that] the letter had been so readily press-released suggests that the intervention is at best virtue signalling and at worst seeking to compromise operational independence”, adding: “Police chiefs know their powers and duties. Anxious and vulnerable minority communities are not made safer by the politicisation of policing in difficult and dangerous times.” Braverman’s letter was sent after Rishi Sunak vowed that anyone in the UK supporting Hamas would be “held to account” in the aftermath of the attack on Israel. The prime minister said the government was ready to support any British citizens in need of help, during a visit in Staffordshire on Tuesday. A “significant number” of British-Israeli dual nationals have been caught up in the conflict in Israel and Gaza, said the foreign secretary, James Cleverly. Sunak confirmed his support for Israel, saying he stood in solidarity with the state and its people “in the face of these barbaric acts of terrorism”. Discussing his visit to a synagogue in north London on Monday night, Sunak said he had been “unequivocal with them that we will make sure that they feel safe at this time”. He said police had “been given very clear guidance and advice from the government to do everything that they can to keep the community safe”. Officers will “clamp down on any behaviour that falls foul of the law”, Sunak said. He added: “I’d just remind everyone that Hamas is a proscribed terrorist organisation. People should not be supporting Hamas and we will make sure that we hold people to account if they are.” The number of Britons caught up in the violence in Israel and Gaza has yet to be confirmed, with ministers wary that official estimates of casualties and those injured are still being compiled. Sunak said he understood there were families in the UK “anxious about their loved ones in the region”. He added: “I want to reassure them we’re doing everything we can, working very closely with the Israeli authorities to establish what is happening on the ground, provide support to people where it’s needed. “I’d urge anyone there to contact the Foreign Office so that they have their details, follow the advice locally from the Israelis but also from the Foreign Office, and we stand ready to support everyone as best we can.” Earlier, Cleverly called on supporters of Palestine to stay at home, after protests in London. The foreign secretary said: “There is no need, there’s no necessity for people to come out. It causes distress. This is a difficult, delicate situation.”