Iranian protesters have stormed and ransacked the Saudi embassy in Tehran in response to the execution of Saudi Shia religious leader Nimr al-Nimr.

Al-Nimr was one of 47 people killed on 2 January as the Saudi government carried out its largest mass execution in decades, causing widespread protests in Shia communities in the region.

Demonstrators broke into the embassy on the morning of 3 January and set fires before being removed by the police, according to Iranian media.

Al-Nimr had been a supporter of mass protests in Saudi Arabia’s Eastern Province since 2011, campaigning for improved rights for the kingdom’s Shia minority. He was said to have a strong following among Saudi Shia youth.

Al-Nimr and the three other Shia executed were accused of being involved in shooting police. Most of the others executed were Sunnis convicted for Al-Qaeda attacks in Saudi Arabia.

The Iranian Foreign Ministry issued a statement condemning the execution of Al-Nimr and urging protection of embassies, according to the country’s Mehr news agency. “Understanding the pure sentiments of Muslim people of our country, the foreign ministry urges restriction from any gathering outside these places,” read part of the statement issued after the Saudi embassy was stormed.

The execution of Al-Nimr has also been condemned outside the Middle East. US State Department spokesman John Kirby urged the kingdom to allow peaceful expression of dissent and to redouble efforts to reduce regional tensions.