“Saudi Arabia profoundly wrong to execute Sheikh Nimr al-Nimr. Opposed to the death penalty and Amnesty had serious concerns about his trial,” Benn said in a message posted on his Twitter account on Saturday.
Meanwhile, Tim Farron, the Liberal Democrat leader, slammed the execution of the Shiite cleric and 46 other people as "abhorrent".
"I utterly condemn Saudi Arabia for the execution of 47 people including the prominent Shiite cleric Sheikh Nimr al-Nimr. Capital punishment is utterly abhorrent and the Prime Minister needs to turn round to our 'ally' and tell them capital punishment is wrong,” Farron was quoted as saying on Saturday.
In addition, British protesters rallied outside the Saudi embassy in London on Saturday and expressed their wrath over the execution of Ayatollah Nimr.
On Saturday, Saudi Arabia executed 47 prisoners, including Sheikh Nimr, the Arab country’s interior ministry said in a statement.
Among them were four Shiite Muslims accused of anti-government protests in recent years.
The executions took place in 12 cities in Saudi Arabia, four prisons using firing squads and the others beheading. The bodies were then hanged from gibbets in the most severe form of punishment available in the kingdom's law.
Sheikh Nimr was detained in July 2012 on charges of delivering anti-regime speeches and defending political prisoners.