Israel has officially announced it will not cooperate with a special commission set up by the UN's highest human rights body to investigate alleged abuses against Palestinians, saying the investigation and its leader are unfairly biased against Israel, AP reported.

The decision, conveyed in a scathing letter to commission chief Navi Pillay, further strained already tense relations between Israel and the UN-backed Human Rights Council.

“It is obvious to my country, as it should be to any fair-minded observer, that there is simply no reason to believe that Israel will receive reasonable, equitable and non-discriminatory treatment from the Council, or from this Commission of Inquiry,” said the letter, signed by Meirav Eilon Shahar, Israel’s ambassador to the U.N. and international organizations in Geneva.

The Council established a three-member commission of inquiry last May, days after the 11-day war between Israel and Hamas in the Gaza Strip. Over 260 Palestinians were killed in the fighting, including many women and children. Fourteen people died in Israel.

At the time, UN High Commissioner for Human Rights Michelle Bachelet said that Israeli actions, including air strikes on civilian areas, could constitute war crimes.

Israel has long accused the United Nations, and especially the Human Rights Council, of bias.

Israel has also repeatedly rejected international calls for an investigation into its actions during the war and its treatment of the Palestinians. The International Criminal Court in The Hague has launched an investigation into possible Israeli war crimes, which Israel says is motivated by 'antisemitism' and is part of an international campaign to "delegitimize" it.