Iraq’s top Shiite authority Grand Ayatollah Sayyed Ali al-Sistani said in a statement on Sunday that the execution of prominent Saudi cleric Ayatollah Sheikh Nimr Baqer al-Nimr is an expression of "aggression and injustice".

Iraq's top Shiite authority Grand Ayatollah Sayyed Ali al-Sistani said in a statement on Sunday that the execution of prominent Saudi cleric Ayatollah Sheikh Nimr Baqer al-Nimr is an expression of "aggression and injustice".

"We received with deep sadness and regret the news of the martyrdom of a group of our brothers in the region," his eminence said.

"The spilling of their pure blood -- including of the martyr Sheikh Nimr al-Nimr, may his soul rest in peace -- is an injustice and an aggression," Ayatollah Sistani said.

The Saudi authorities executed on Saturday Sheikh Nimr along with 46 other people. He was a vocal supporter of the mass pro-democracy protests against Riyadh regime, that erupted in Eastern Province in 2011, where local residents has long complained of marginalization.