https://www.bbc.co.uk/news/uk-67517410photo
The Met Police are to clarify what type of language might break the law when chanted or displayed at pro-Palestinian marches.
The force will hand out leaflets at Saturday's march in central London warning against using words or images "likely to land you in jail".
It is the first time the Met has tried to give clarity on what language is unacceptable.
Organisers say at least 100,000 people could turn out for the protest.
The Met has [size=inherit]
previously been criticised[/size] over its handling of the pro-Palestinian protests - which have been held weekly since 14 October - with ministers calling for the force to take a tougher line on those deemed to be expressing extremist views.
The force is also planning to position Arabic-speaking officers on the march, backed up in its central control room with lawyers to advise on whether specific phrases break the law.
Some 1,500 officers will be on the streets on Saturday with instructions to protect war memorials following criticism that police have not stopped protesters climbing on them.