Thousands of people joined a pro-Palestinian march in London calling for a ceasefire in Gaza.
Organisers said the protest was part of a global day of action in 30 countries.
More than 1,700 police officers were on duty to manage the march from London’s commercial centre to Westminster.
Six people have been arrested for a range of alleged offences, the Metropolitan Police said.
“Two for offensive placards, one for being in possession of stickers to be used for criminal damage and the three arrested under the Terrorism Act,” the Met said on social media.
Ahead of the march, Deputy Assistant Commissioner Laurence Taylor from the Met warned people who “intentionally push the limit” on placards or chanting slogans that they face arrest.
Alongside the heavy police presence, including forces from outside of London, police handed out flyers to protesters which said “keep on the right side of the law”.
This was the seventh national pro-Palestinian march held in London following the unprecedented Hamas attacks on southern Israel on 7 October which led to around 1,300 people being killed and more than 240 kidnapped.
More than 23,000 people have been killed in Gaza since Israel began its retaliatory bombing campaign and launched a subsequent ground campaign, according to the Hamas-run health ministry.
Protests have taken place most weekends in the British capital and have been attended by tens of thousands of largely peaceful people.
But there have been dozens of arrests for a variety of public order offences, including people chanting or carrying placards with antisemitic slogans and for supporting Hamas – which is a proscribed terrorist organisation in the UK.
The Met also placed some limits on the protest – like marchers must stick to the route to Parliament Square and speeches need to be finished by 16:30 GMT.
Protesters were also banned from entering the area around the Israeli embassy in Kensington.
Home Secretary James Cleverly said he had been briefed by Met Commissioner Sir Mark Rowley over the force’s plans to “ensure order and safety” on Saturday.
“I back them to use their powers to manage the protest and crack down on any criminality,” Cleverly said.
A giant puppet of a Syrian child refugee, known as Little Amal, joined a group of children on the march to bring focus on the suffering of children in Gaza.
The 3.5m (11ft) tall puppet became an international symbol of human rights after she journeyed thousands of miles from the Turkish-Syrian border to Manchester in July 2021.
Former Labour leader Jeremy Corbyn addressed the crowd calling for a ceasefire.
London is one of 30 countries taking part in the Global Day of Action protestshttps://menghadapimu.com/ – elsewhere people have gathered in parts of Indonesia and Thailand.
On Sunday there will be a rally in support of Israel taking place in London’s Trafalgar Square.