TEHRAN, Nov. 29 (Xinhua) -- Following the recent killing of its top nuclear scientist, Iran has condemned the violence and vowed punishment, while regional countries and global bodies have expressed concern over rising tensions in the region and urged restraint.

On Friday, high-ranking Iranian nuclear physicist Mohsen Fakhrizadeh was assassinated near the capital city of Tehran by "armed terrorists," according to the Iranian Ministry of Defense.

"The Iranian nation will not allow the crime to remain unanswered," Iranian President Hassan Rouhani was quoted by official IRNA news agency as saying, adding that his country will respond to the assassination at an "appropriate" time.

Iran's Supreme Leader Ayatollah Ali Khamenei on Saturday called on the authorities to seriously "probe this crime and punish the perpetrators," noting that the scientific and technological efforts of Fakhrizadeh will continue.

"We urge restraint and the need to avoid any actions that could lead to an escalation of tensions in the region," said Farhan Haq, deputy spokesman for UN Secretary-General Antonio Guterres, on Friday.

"Turkey opposes any attempt to disturb peace and tranquility in the region, as well as against all types of terrorism, regardless of who the perpetrator or target is," the Turkish Foreign Ministry said in a statement, adding that all those responsible must be held accountable.

Strongly condemning the attack, the European Union called it a "criminal act," according to media.

As no one has claimed responsibility for the assassination, the Iranian government suspected that it was performed by Israel's Mossad intelligence agency, said media reports.

Israel has so far neither confirmed nor denied the allegation.