Photo taken on Sept. 14, 2020 shows the outside view of the United Nations headquarters in New York, the United States. (Xinhua/Wang Ying)

"We have noted the reports that an Iranian nuclear scientist has been assassinated near Tehran today. We urge restraint and the need to avoid any actions that could lead to an escalation of tensions in the region," a UN spokesman said.

UNITED NATIONS, Nov. 28  -- A United Nations spokesman on Friday called for exercising restraint and avoiding escalation in the Middle East region following the assassination of top Iranian nuclear scientist Mohsen Fakhrizadeh.

"We have noted the reports that an Iranian nuclear scientist has been assassinated near Tehran today. We urge restraint and the need to avoid any actions that could lead to an escalation of tensions in the region," Farhan Haq, deputy spokesman for UN Secretary-General Antonio Guterres, said when responding to a question related to the assassination.

In a letter to Guterres and Inga Rhonda King, president of the Security Council for the month of November, Iran's permanent representative to the United Nations Majid Takht Ravanchi expressed strong condemnation against the "criminal assassination" of its nuclear scientist.

He added Iran "expects the secretary-general of the United Nations and the Security Council to strongly condemn this inhumane terrorist act and take necessary measures against its perpetrators."

Takht Ravanchi noted in the letter that "one of the latest services of Martyr Fakhrizadeh was his outstanding role in the development of the first indigenous COVID-19 Test Kit, which is a great contribution to our national efforts in curbing the COVID-19 pandemic at a time when Iran is under inhumane sanctions of the United States, strictly preventing our access to humanitarian goods including medicines and medical equipment."