Iran’s powerful Revolutionary Guards have warned Saudi Arabia that they will suffer a “harsh revenge” following the execution of Sheikh Nimr al-Nimr.
Iran have warned that “the unjustly spilled blood of this oppressed martyr will no doubt soon show its effect and divine vengeance will befall Saudi politicians.”
The move appeared to end any hopes that the common enemy of ISIS could lead to rapprochement between the two countries.
Nimr was considered a terrorist by Riyadh but hailed in Iran as a champion of the rights of Saudi Arabia’s marginalised Shia Muslim minority.
Outraged Iranian protesters stormed the Saudi Embassy in Tehran early on Sunday morning leaving a trail of destruction
One photograph posted on Twitter showed a baying mob outside the embassy with small fires burning inside.
Another showed a room inside the building with smashed furniture strewn across the floor.
The scenes bore a striking resemblance to the 1979 hostage crisis in which 52 Americans were held for 444 days when a group of Iranian students stormed the US embassy.
Shortly afterwards, Iran’s Foreign Ministry issued a statement calling for calm and urging protesters to respect the diplomatic premises.
The executions have drawn international condemnation, with United Nations secretary general Ban Ki-moon saying he was “deeply dismayed” by Saudi’s actions.
He said: “Sheik al-Nimr and a number of the other prisoners executed had been convicted following trials that raised serious concerns over the nature of the charges and the fairness of the process.
Ban had raised Nimr’s case with Saudi leaders on a number of occasions and urged the country to commute all death sentences that had been imposed, a spokesman said.