Pro-Palestinian demonstrators staged protests in London, Berlin, Paris, Ankara and Washington to call for a ceasefire in Gaza and castigate Israel after its military intensified its assault against Hamas.
In London, television footage showed large crowds holding sit-down protests blocking parts of the city centre, before marching to Trafalgar Square.
Protesters held "Freedom for Palestine" placards and chanted "ceasefire now" and "in our thousands, in our millions, we are all Palestinians."
Police said they made 29 arrests for offences including inciting racial hatred and racially aggravated public order.
Echoing Washington's stance, Prime Minister Rishi Sunak's government has stopped short of calling for a ceasefire, and instead advocated humanitarian pauses to allow aid into Gaza.
On Sunday, Turkish police fired tear gas to disperse a pro-Palestinian rally staged outside a military base housing US force just hours before the arrival in Ankara of Washington's top diplomat.
The protest outside the Incirlik Air Base in southeastern Turkey was organized by the IHH humanitarian relief fund, which in 2010 led a flotilla to Gaza that sparked Israeli raids in which 10 civilians died.
In United States, thousands of protesters marched down the streets of Washington waving Palestinian flags, some chanting "Biden, Biden you cannot hide, you signed up for genocide," before congregating at Freedom Plaza, steps away from the White House.
Speakers denounced President Joe Biden's support of Israel, declaring "you have blood on your hands." Some vowed not to support Biden's bid for a second term in the White House next year as well as campaigns by other Democrats seeking office, calling them "two-faced" liberals who were "not a refuge from right wingers."
Others lashed out at civil rights leaders for not condemning the killing of women and children by Israeli bombings.
In central Paris, thousands marched to call for a ceasefire with placards reading "Stop the cycle of violence" and "To do nothing, to say nothing is to be complicit."
It was one of the first, big gatherings in support of Palestinians to be legally allowed in Paris. French authorities had banned some previous pro-Palestinian gatherings due to concerns about public disorder.
In Berlin, demonstrators waved Palestinian flags, demanding a ceasefire. One woman marched with her arm in the air, her hand covered in fake blood.
