Riyadh - Saudi Arabia's execution on Saturday of 47 prisoners, including an influential Shiite cleric, threatened to further damage Sunni-Shiite relations in a regional struggle playing out across the Middle East between the kingdom and its regional foe Iran.
Shiite leaders in Iran and other countries across the region swiftly condemned Riyadh and warned of sectarian backlash as Saudi Arabia insisted the executions were part of a justified war on terrorism. Also executed Saturday were al-Qaeda detainees who were convicted of launching a spate of attacks against foreigners and security forces a decade ago.
In Tehran, a large crowd upset over the execution of Sheikh Nimr al-Nimr gathered outside the Saudi embassy and chanted anti-Saudi slogans. Some protesters threw stones and Molotov cocktails at the embassy, setting off a fire in part of the building, Iran's top police official, General Hossein Sajedinia, told the semi-official Tasnim news agency early Sunday.
Some of the protesters broke into the embassy and threw papers off the roof, and police worked to disperse the crowd, Sajedinia told the semi-official ISNA news agency. He later told Tasnim that police had removed the protesters from the building and arrested some of them. He said the situation outside the embassy "had been defused."
Al-Nimr's execution promises to open a rancorous new chapter in the ongoing Sunni-Shiite power struggle playing out across the Middle East, with Saudi Arabia and Iran as the primary antagonists. The two regional powers already back opposing sides in civil wars in Yemen and in Syria. Saudi Arabia was also a vocal critic of the recent Iranian agreement with world powers that ends international economic sanctions in exchange for limits on the Iranian nuclear program.
Iranian politicians warned that the Saudi monarchy would pay a heavy price for the death of al-Nimr. The Iranian Foreign Ministry summoned the Saudi envoy in Tehran to protest, and parliament speaker Ali Larijani said the execution would prompt "a maelstrom" in Saudi Arabia.
The Saudi Foreign Ministry later said it had summoned Iran's envoy to the kingdom to protest the critical Iranian reaction to the sheikh's execution, saying it represented "blatant interference" in its internal affairs.