The statue of Sir Winston Churchill in Parliament Square in Westminster was defaced overnight with "Zionist war criminal" and other graffiti.
A 38-year-old man has been arrested on suspicion of racially aggravated criminal damage and remains in custody.
Officers from the Metropolitan Police were alerted shortly after 4am on Friday morning.
Other phrases including "Stop the Genocide" and "Free Palestine" were sprayed in red paint on the bronze sculpture.
Further graffiti read "Never again is Now" and "Globalise the Intifada".
The statue has been cordoned off and was being cleaned this morning.
Commenting on the image, which was shared on X, Dave Rich, director of policy for Community Security Trust, posted: "Free Palestine" and a Hamas red triangle, if you zoom in close enough. This extremism is never just a threat to Jews."
Read more from Sky News:
Netflix withdraws Warner Bros bid
We are in a new era of multi-party politics
The Jewish Leadership Council said it was "disgusted" by the defacing of the statue.
It said on X: "In targeting the statue of a British hero who led this country in the fight against the Nazis, the perpetrator has found a perverse way to combine a hatred of Jews with a disdain for Britain."
Phil Rosenberg, president of the Board of Deputies of British Jews, wrote: "One of the greatest champions for liberty, who defeated the Nazis, defaced.
"Zionism, the national liberation movement of the Jewish people, inverted.
"Santayana's "Those who cannot remember the past are condemned to repeat it", never truer."
The 12ft-tall statue on the north-east corner of the square, created by Ivor Roberts-Jones, was unveiled in 1973 by the former prime minister's wife, Lady Clementine Churchill.
It is one of 12 statues on or around Parliament Square, most of well-known statesmen such as Nelson Mandela and Abraham Lincoln.
The former prime minister's statue has been vandalised several times over the years, including during demonstrations.
Last December both the Metropolitan Police and Greater Manchester Police announced anyone chanting "globalise the intifada" would face arrest.
The decision by the two police forces came in the wake of the Bondi Beach terror attack, and the terror attack at Heaton Park synagogue in Manchester on 2 October.
(c) Sky News 2026: Man, 38, arrested after Churchill statue defaced with 'Zionist war criminal'


Ukraine's Volodymyr Zelenskyy tells Sky News he's ready to meet Putin for peace talks but won't give up territory
AI willing to 'go nuclear' in wargames, study finds - amid 'stand-off' between Pentagon and leading AI lab
Iran and US compromise over nuclear stockpile - but Trump's window for action grows smaller by the day
The Epstein committee shouldn't be defined by politics - but it is hard to avoid