“The unjustly spilled blood of this oppressed martyr will no doubt soon show its effect and divine vengeance will befall Saudi politicians,” state TV reported Khamenei as saying. It said he described the execution as a “political error”.

Saudi Arabia executed Nimr al-Nimr and three other Shi’ites alongside dozens of al Qaeda members on Saturday, signalling it would not tolerate attacks by either Sunni jihadists or members of the Shi’ite minority seeking equality.

Khamenei added: “This oppressed cleric did not encourage people to join an armed movement, nor did he engage in secret plotting, and he only voiced public criticism … based on religious fervour.”

In an apparent swipe at Saudi Arabia’s Western allies, Khamenei criticised “the silence of the supposed backers of freedom, democracy and human rights” over the execution.

“Why are those who claim to support human rights quiet? Why do those who claim to back freedom and democracy support this (Saudi) government?” Khamenei was quoted as saying.

While Western human rights groups have condemned the executions, Western government responses have so far been muted.

The U.S. State Department expressed concern that Nimr’s execution could exacerbate sectarian tensions in the Middle East. In Hawaii, where President Barack Obama is on vacation with his family, White House deputy national security adviser Ben Rhodes said the administration has urged the Saudis to show restraint regarding respect for human rights.

Angry Iranian protesters stormed Saudi Arabia’s embassy in Tehran in the early hours of Sunday, smashing furniture and starting fires before being removed by the police.

The protesters had gathered outside the embassy to protest against Saudi Arabia’s execution of Nimr al-Nimr, a prominent cleric from the kingdom’s Shi’ite minority, on terrorism charges that Iran said were unjustified.

They then broke into the building and lit fires inside before being cleared by police, the ISNA news agency reported. Images shared on social media appeared to show protesters smashing furniture inside the embassy.

Later images showed police in full riot gear guarding the premises as firefighters doused the building. ISNA said Tehran’s police chief was on the scene to restore calm.

Iranian Foreign Ministry spokesman Hossein Jaber Ansari called for calm and said there should be no more demonstrations around Saudi diplomatic premises, the state news agency IRNA reported. DM

Photo: Smoke rises from Saudi Arabia’s embassy during a demonstration in Tehran January 2, 2016. Iranian protesters stormed the Saudi Embassy in Tehran early on Sunday morning as Shi’ite Muslim Iran reacted with fury to Saudi Arabia’s execution of a prominent Shi’ite cleric. REUTERS/TIMA/Mehdi Ghasemi