Palestinian leaders said on Tuesday Britain had rejected their request for an apology for a 1917 declaration that helped pave the way to the state of Israel, and they would pursue international court action unless London backtracked.

Palestinian President Mahmoud Abbas called for the apology in an address to the U.N. General Assembly in September, but Britain plans to hold celebrations along with Israeli officials to mark the Nov. 2 centenary of the Balfour Declaration.

“The answer came in a written letter to the (Palestinian) Foreign Ministry that the apology is refused,” Manuel Hassassian, the Palestinian ambassador to Britain, told Voice of Palestine Radio on Tuesday.

“It means the Queen and the government of Britain will not apologize to the Palestinian people.”

In the 1917 declaration, the British government said it viewed “with favor the establishment in Palestine of a national home for the Jewish people.” It also said .”..nothing shall be done which may prejudice the civil and religious rights of existing non-Jewish communities in Palestine…”

Palestine was under British rule when Foreign Secretary Arthur Balfour made the policy statement in a letter to Lord Rothschild, a leader of the British Jewish community.