Unverified footage posted on social media appears to show part of the Saudi Embassy in Tehran under attack and on fire. <br />Protests in the Iranian capital follow the execution of a prominent Shia cleric, Sheikh Nimr al-Nimr, in Saudi Arabia. <br />Iran's supreme leader Ayatollah Ali Khamenei described Sheikh Nimr as a "martyr" who acted peacefully, and warned Saudi Arabia will face "divine revenge".
