Manchester: British Prime Minister David Cameron has urged Middle East ally Saudi Arabia on Sunday not to go ahead with the execution of a Shiite Muslim sentenced to death over his role in anti-government protests.

"Don't do it," Mr Cameron said when asked about the case of Ali al-Nimr, who was handed the death penalty after taking part in demonstrations in Saudi Arabia's oil-producing Eastern Province.

Ali Mohammed al-Nimr was sentenced to death by beheading and crucifixion in Saudi Arabia after taking part in protests in 2012 and, despite international pressure to commute the sentence, remains on death row. Credit:Reprieve

Not only was Mr Nimr handed a death sentence, but the method of punishment was determined to be crucifixion, which human rights groups say means he will be beheaded and then have his mutilated body displayed publicly.