Hashem al Darwish was convicted for protest-related offences, many of which took place when he was 17. He was arrested in May 2015. He was executed on Tuesday in Dammam, a statement from the Ministry of Interior said.

Last year, Saudi authorities had said they would stop sentencing to death people who committed crimes while being underage and instead they would serve 10 years in jail in juvenile detention, said an Al Jazeera report.

“The execution of Mustafa al-Darwish once again shows that the Kingdom’s claim to have eliminated capital punishment for childhood crimes is not true,” anti-death penalty and human rights group Reprieve said in a statement.

In February, the state-backed Human Rights Commission told Reuters that the ban only applied to a lesser category of offence under Islamic law known as “ta’zeer.”

Darwish was convicted for “ta’zeer” offences, the Al jazeera report stated.

According to Reuters, Darwish was accused of “participating in armed rebellion”, “seeking to disturb security by rioting” and “sowing discord”, among others.

The evidence, including signed confession and photographs, indicated his participation in more than 10 “riot” gatherings in 2011 and 2012 but do not mention the exact months of the alleged offences.

Reprieve and Amnesty International said the signed confession was obtained under duress and he recanted his confession in court.

His family was not given advance notice and learned only after his execution, according to Reprieve.

Another non-profit organisation fighting for human rights in Saudi Arabia tweeted: "Today, the #Saudi authorities executed Mustafa Hashem al-Darwish, a young man who was arrested in 2015 on charges relating to participating in Qatif protests when he may have been a minor. Over 40 detainees in #SaudiArabia, including minors, remain at risk of the death penalty."

Western legislators and Human Rights organisations have raised concerns over the implementation of the reforms.

A group of British MPs urged UK Foreign Secretary Dominic Raab to ask for commutation of Darwish's sentence during his visit to Riyadh.

The US had expressed  concern over the execution of Shia cleric Sheikh Nimr al-Nimr by Saudi Arabia in 2016.

He was a supporter of the mass anti-government protests which had erupted in Eastern Province in 2011.

His execition, along with 47 others, sparked protests in Pakistan to Iran, where Saudi embassy was ransacked.