United Nations, Nov 28 : A UN spokesman has 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, the deputy spokesman for UN Secretary-General Antonio Guterres, said when responding to a question related to the assassination on Friday. In a letter to UN Secretary-General Antonio Guterres and Inga Rhonda King, President of the Security Council for the month of November, Iran's permanent representative to the UN Majid Takht Ravanchi expressed strong condemnation against the "criminal assassination" of its nuclear scientist. He added Iran "expects the Secretary-General of the UN and the Security Council to strongly condemn this inhumane terrorist act and take necessary measures against its perpetrators", A professor of physics at Imam Hussein University of Tehran, Fakhrizadeh, dubbed the "father of the Iranian bomb", was assassinated near the capital city on Friday by "armed terrorists", the country's Ministry of Defence announced. The Ministry's media office said Fakhrizadeh "was severely wounded in the course of clashes between his security team and terrorists, and was transferred to hospital", where he succumbed to his injuries. Fakhrizadeh also headed the Defence Ministry's Organization of Defensive Innovation and Research (SPND). The Iranian government suspects that the assassination was conducted by Israel's Mossad intelligence agency, though Tel Aviv has neither confirmed nor denied the allegation, according to media reports. /IANS