UNITED NATIONS, March 31 (Xinhua) -- The United Nations on Friday issued a statement, welcoming efforts leading to peaceful settlement of Nagorno-Karabakh conflict.

Farhan Haq, Deputy Spokesman for UN Secretary-General Antonio Guterres, said in a press release that the UN had noted the recent statements by the Co-Chairs of the OSCE Minsk Group and by the OSCE Chairperson-in-Office and expressed "full support" for the call to the sides to refrain from any actions that would undermine the ceasefire agreement.

"We welcome all efforts to reduce the level of tensions and call on all sides to demonstrate the necessary political will to resume substantive negotiations leading to a peaceful settlement of the Nagorno-Karabakh conflict," he said.

The Nagorno-Karabakh conflict entered its modern phase when the Armenian SRR (Armenian Soviet Socialist Republic) made territorial claims against the Azerbaijani SSR in 1988.

A fierce war broke out between Azerbaijan and Armenia over the Nagorno-Karabakh region. As a result of the war, Armenian armed forces occupied some 20 percent of Azerbaijani territory which includes Nagorno-Karabakh and seven adjacent districts, and over a million Azerbaijanis became refugees and internally displaced people.

The military operations finally came to an end when Azerbaijan and Armenia signed a ceasefire agreement in Bishkek in 1994.

Dealing with the settlement of the Nagorno-Karabakh conflict is the OSCE Minsk Group, which was created after the meeting of the CSCE Ministerial Council in Helsinki on March 24, 1992.

Besides, the OSCE Minsk Group has a co-chairmanship institution, comprised of Russian, the U.S. and French co-chairs, which began operating in 1996.

Resolutions 822, 853, 874 and 884 of the UN Security Council, which were passed in short intervals in 1993, and other resolutions adopted by the UN General Assembly, PACE, OSCE, OIC, and other organizations require Armenia to unconditionally withdraw its troops from Nagorno-Karabakh.