Iran's top leader on Sunday warned Saudi Arabia of "divine revenge" over the execution of an opposition Shiite cleric while Riyadh accused Tehran of supporting terrorism, escalating a war of words hours after protesters stormed the Saudi Embassy in Tehran. The execution of Sheikh Nimr al-Nimr on Saturday along with 46 others was the largest mass execution in three and a half decades, and drew condemnation from Shiites across the region. Iran's Supreme Leader Ayatollah Ali Khamenei said al-Nimr "neither invited people to take up arms nor hatched covert plots. The only thing he did was public criticism." Iran's powerful Revolutionary Guard said Saudi Arabia's "medieval act of savagery" in executing the cleric would lead to the "downfall" of its monarchy.
Saudi Arabia's Foreign Ministry said Iran "revealed its true face represented in support for terrorism," and that "by its defense of terrorist acts" Iran is a "partner in their crimes in the entire region." The Iranian Foreign Ministry summoned the Saudi envoy in Tehran, while the Saudi Foreign Ministry later summoned Iran's envoy. In Tehran, a crowd gathered outside the Saudi Embassy early Sunday, with some throwing stones and Molotov cocktails, setting off a fire. A top police official said police removed the protesters and arrested some, adding that the situation had been "defused." Hours later, a Tehran prosecutor said 40 people had been arrested. Iraq's top Shiite cleric, Grand Ayatollah Ali al-Sistani, called al-Nimr a martyr and said his blood and that of other Shiite protesters "was unjustly and aggressively shed."