Flames rise from Saudi Arabia's embassy during a demonstration in Tehran
Flames rise from Saudi Arabia's embassy during a demonstration in Tehran Reuters

Iran on Monday expressed “regret” over two attacks on Saudi Arabian diplomatic missions in its country, saying it will spare no effort in arresting and prosecuting those responsible, reports The Associated Press (AP).

Iran’s UN envoy Gholamali Khoshroo said in a letter to UN Secretary-General Ban Ki-moon that the Islamic Republic “will take necessary measures to prevent the occurrence of similar incidents in the future.”

Saudi Arabia severed ties with Iran on Sunday after protesters attacked its embassy in Tehran and consulate in Mashad.

Iranian fanatics turned violent to protest Saudi Arabia’s execution of prominent opposition Shiite cleric Nimr al-Nimr, which the predominantly Shiite Iran - Saudi Arabia’s regional rival - has denounced.

According to AP, Khoshroo said more than 40 protesters at the embassy have been arrested and handed over to judicial authorities and that investigators are seeking other possible perpetrators.

In the letter, obtained by the news agency, he said Iran supports the Vienna conventions on the protection of diplomats and diplomatic property. Khoshroo asked that the letter be circulated to all 193 UN member nations.

Nimr was a driving force of the protests that broke out in 2011 in Eastern Province, where the Shiite minority of Saudi Arabia complains of marginalization.

He was arrested in 2012, with the Interior Ministry describing him as an "instigator of sedition".

Iranian Supreme Leader Ayatollah Ali Khamenei blasted Saudi Arabia over the execution of Nimr on Sunday,, saying, “The hand of God will take vengeance against Saudi leaders.”

Khamenei told Iranian national TV that “for the unjust spilling of blood of this holy man, who suffered and was downtrodden, there will no doubt be heavenly vengeance taken upon Saudi politicians.”

UN Secretary-General Ban Ki-moon has urged Saudi Arabia and Iran to support peace efforts in Syria and Yemen and avoid escalating tensions, according to AP.

UN spokesman Stephane Dujarric said Ban delivered this message in phone calls to Iranian Foreign Minister Mohammad Javad Zarif on Sunday and to Saudi Foreign Minister Adel Al-Jubeir on Monday.

Dujarric said the UN chief called for all political and religious leaders in the region “to avoid adding fuel to the fire.”