A portrait of Lord Balfour, the former British prime minister, at the University of Cambridge has been damaged by a pro-Palestinian protester.

In video posted on social media by Palestine Action, a member of the group is seen spray-painting and slashing the portrait at Trinity College. A woman can be seen defacing the work with red paint before slicing the canvas with a sharp object.

Balfour was one of the chief supporters of creating a Jewish homeland in Palestine, cemented by the Balfour Declaration of 1917, which gave British backing to the movement.

The Instagram video was accompanied by a caption that read: “Palestine Action spray and slash a historic painting of ‘Lord’ Balfour in Trinity College, University of Cambridge.

“Written in 1917, Balfour’s declaration began the ethnic cleansing of Palestine by promising the land away – which the British never had the right to do.

“The British paved the way for the Nakba and trained the Zionist militia to ethnically cleansed over 750,000 Palestinians, destroy over 500 villages and massacre many families. The Nakba never stopped, and the genocide today is rooted and supported by British complicity.

A Trinity College spokesman said: “Trinity College regrets the damage caused to a portrait of Arthur James Balfour during public opening hours. The police have been informed. Support is available for any member of the College community affected.”

A spokesman for Cambridge Police said: “This afternoon we received an online report of criminal damage today to a painting at Trinity College, Cambridge.