Protesters had gathered at noon before marching through the streets of Westminster, bringing traffic to a halt.
A man was arrested on suspicion of making threats to kill as at least 100,000 pro-Palestinian protesters took to the streets of central London demanding a ceasefire in the Israel-Hamas war.
Flags and banners were waved, flares were lit and fireworks were let off as the mostly peaceful group of demonstrators snaked through the closed-off roads in Westminster on Saturday afternoon.
Around 1,000 officers policed the event, which saw two confirmed arrests.
One man was detained on Whitehall after a police officer was assaulted, the Metropolitan Police said.
The force said the officer was taken to hospital following the incident.
Another man was arrested in Waterloo Road on suspicion of a racially aggravated public order offence and making threats to kill.
Police were seen clashing with pro-Palestinian protesters close to Downing Street.
Officers appeared to be detaining someone before demonstrators began scuffling with them.
Punches and kicks were thrown and officers ordered the protesters to move away.
One person was taken to the floor and carried away to chants of “let him go” from other protesters.
Cries of “Allahu akbar”, the Arabic phrase for “God is great”, also rang out.
Some protesters chanted “from the river to the sea, Palestine will be free”, despite controversy around the slogan’s meaning.
Home Secretary Suella Braverman has previously branded the slogan anti-semitic and claimed that it is “widely understood” to call for the destruction of Israel.
However, pro-Palestinian protesters have contested this definition.
Counter demonstrations were also taking place, with dozens of people with Union flags standing close to the Cenotaph on Whitehall, drawing chants of “shame on you” from pro-Palestinian marchers.
The counter-protesters could be heard chanting back “free Palestine from Hamas”.
Meanwhile, the nearby Earl Haig Memorial statue was graffitied with the words “God save Gaza”.
It came after a woman was knocked over by a police horse after the animal was startled by fireworks, but appeared to be fine when she was brought back to her feet.
Protesters had gathered at noon before marching through the streets of Westminster, bringing traffic to a halt.
Former Labour leader Jeremy Corbyn was among the politicians who addressed them on a stage in Parliament Square.
He said: “The world’s nations voted at the United Nations last night in the General Assembly by an overwhelming majority to demand a ceasefire.
“It’s not much to ask, a ceasefire when children are being killed by weapons coming through the rooms of their homes.
“It is in eternal stain that the British Government abstained on that vote.”
A Section 60 and Section 60AA authority was later put in place until midnight, giving police stop and search powers in the London boroughs of the City of Westminster and Kensington and Chelsea.
Section 60 AA requires a person to remove items that might be used to conceal their identity, such as masks.
Protests also took place in Manchester, Glasgow, Belfast and other cities.
