TEHRAN: Saudi Arabia's decision to cut ties with Iran after attacks on the kingdom's diplomatic missions in the Islamic Republic will not distract from Riyadh's "big mistake" of executing top Shia cleric Nimr al-Nimr, a senior Iranian official said Monday.

"By deciding to sever (diplomatic) relations, Saudi Arabia cannot make (the world) forget its big mistake of executing a cleric," deputy foreign minister Hossein Amir Abdollahian said, according to the IRNA agency.

He added that Saudi Arabia had committed a "strategic error in adopting rash and hasty decisions that have spread instability and caused the development of terrorism in the region".

Riyadh's execution of Nimr al-Nimr sparked widespread protests across Shia-majority countries in the Middle East, with a mob attacking the Saudi embassy in Tehran and a consulate in the second city Mashhad.

The assaults on the diplomatic missions spurred the Arab kingdom to sever ties with Iran, its long-time regional rival.

In recent years, the two countries have been divided over the war in Syria and the conflict in Yemen where a Saudi-led coalition is battling Houthi rebels.

Abdollahian also said Saudi Arabia was "undermining the interests of its own people and the Muslim people of the region with its plot to bring down oil prices", referencing crude prices that are near multi-year lows.

Iran and Saudi are major producers, but Riyadh's current level of crude output far outpaces that of the Islamic Republic and it is seen as a heavyweight in its ability to help set the direction of oil prices.