UK Labour leader Jeremy Corbyn says the UK must recognize Palestine as a state, criticizing the British government for celebrating the 100-year anniversary of the Balfour Declaration.

On Saturday, the vocal British politician attended a pro-Palestinian rally in London, two days after refusing to participate in a series of events held by Prime Minister Theresa May to commemorate the centenary of the 1917 Balfour Declaration, a document that paved the way for Israel’s creation.

Corbyn told a crown that the right way to mark the centenary was for the UK government to recognize Palestine as a state.

“Let us mark the Balfour anniversary by recognizing Palestine as a step toward a genuine two-state solution to the Israel-Palestine conflict,” he said.

“We must increase international pressure for an end to the 50-year occupation of the Palestinian territories, illegal settlement expansion and, of course, the blockade of Gaza,” he added.

The British leader argued that lasting peace in the Middle East can achieve only through a “negotiated settlement” to the Israeli-Palestinian conflict.

The world had a “special responsibility to the Palestinian people who are still denied their basic rights,” he said.

Protesters, while holding signs that read “Free Palestine” and Justice for Palestine”, gathered outside the U.S. embassy in London before marching towards Trafalgar Square, urging the British government to apologize for Balfour Declaration.