People who deviate from a designated route during a pro-Palestinian demonstration in central London on Saturday could face arrest, the Metropolitan Police has warned as the force readies more than 1,000 officers to police the march.

Thousands of people are expected to march in solidarity with Palestine and demand Israel ends its occupation of Palestinian land, amid the ongoing Israel-Hamas conflict.

Starting at Portland Place at 12pm, protesters will march through London before finishing in Whitehall at about 3pm.

The Met warned on X, formerly known as Twitter, on Friday evening that a Section 12 has been authorised from midday on Saturday in the relevant area.

“Any person participating in or associated with the ‘Palestine Solidarity Campaign’ protest must not deviate from the route below or they may be subject to arrest,” the force said.

It also warned that waving a proscribed flag in support of Hamas or other proscribed organisations at the protest will be an offence.

Jonathan Hall KC, the independent reviewer of terrorism, told the BBC that several speeches made at pro-Palestinian rallies that have already taken place in the UK – collected by BBC Verify – might have glorified terrorism and appear to be in breach of terrorism legislation.

Met Police Deputy Assistant Commissioner Laurence Taylor told a press briefing earlier on Friday: “It’s not unusual for London to host protests of that size – almost every week we are hosting very large protests – and I have got a very experienced command team working on this one because of all of the sensitivities and the context in which this protest is taking place.”

Protest liaison teams have been working with organisers to determine what will and will not be acceptable for the Met and how the events can be carried out safely.

Mr Taylor said it is the Met’s job to “balance the right of lawful protest against what that protest is doing”, as it is often individuals within a protest who breach lines of criminality rather than the protest itself.

He added: “Whilst people have the right to protest, they do not have the right to incite violence, they do not have the right to incite hatred and they do not have the right to commit criminal offences and we will robustly police that situation.”

Having and waving a Palestinian flag alone will not be an offence but it could form part of one if it is associated with words or actions inciting violence.

Mr Taylor said this creates “really tricky lines” for policing and the Met has asked the Attorney General and Crown Prosecution Service for “absolute clarity and guidance” on the issue, with a written response expected before the protest.

He also told of a “massive increase” in antisemitic crime and incidents since the Israel-Hamas conflict including an incident on Monday evening where Jewish individuals were confronted by members of a protest group, “effectively playing up the issues in Israel and laughing about the number of deaths of Jewish citizens in Israel”.

Mr Taylor said the force has seen an increase in Islamophobic incidents as well, “but nothing like the scale of the increase in antisemitism”.

The march on Saturday follows calls from Prime Minister Rishi Sunak on Israel to “protect ordinary Palestinians and facilitate humanitarian aid” and from the Archbishop of Canterbury for a Gaza humanitarian corridor.