The father of a Saudi activist, who faces execution by beheading and possibly crucifixion for taking part in pro-reform protests, appealed to King Salman on the occasion of Islam’s most important holiday to spare his son’s life.

The case of Ali al-Nimr, who was only 17 when he was arrested in February 2012, has drawn international condemnation. Critics have also alleged that he was tortured into confessing that he joined "a criminal group" and attacked police forces. Nimr’s is the latest case to highlight widespread human rights abuses in the hardline kingdom, which Amnesty International calls one of the world's most prolific executioners.

Mohammed al-Nimr, Ali’s father, said in an interview with Agence France-Presse (AFP) news agency that he hoped the king would pardon his son.

"We hope that the king will not sign" the execution order, Mohammed said, after Saudi Arabia's highest court confirmed the death sentence last week, leaving his son's fate in the monarch's hands.

Mohammed warned that if his son is put to death, Saudi’s Shia minority could react violently, something he does not want to happen. "We don't need that; we don't need even one drop of blood," he said.

The younger Nimr is a nephew of Nimr al-Nimr, a prominent Shia religious leader who is also on death row. Mohammed al-Nimr, a businessman from Dammam in eastern Saudi Arabia, was in Riyadh to visit his jailed brother for the Muslim feast of sacrifice, Eid al-Adha, which fell on Thursday.

Nimr al-Nimr was a driving force behind demonstrations that began four years ago in Eastern Province, where most of Sunni-dominated Saudi Arabia's Shias live. Residents there complain of political marginalization, namely that they are frequently branded as Iranian agents by Saudi hardliners.

Mohammed admitted that his son, then a high school student, had joined thousands of other people in protests. But he insisted that Ali was innocent on numerous other charges including burglary, attacking police and using a Molotov cocktail.

The court sentenced Ali to death but gave no further details. Execution in the kingdom is usually carried out by sword, sometimes in public, and there are reports his body will subsequently be crucified.

On Tuesday, U.N. rights experts called for Ali's life to be spared. They said in a statement that the teen was reportedly tortured, coerced into a confession and denied adequate access to a lawyer before and during a trial that did not meet international standards.

"Any judgment imposing the death penalty upon persons who were children at the time of the offence, and their execution, are incompatible with Saudi Arabia’s international obligations," the experts said.

Saudi Arabia has executed 133 locals and foreigners this year, according to a tally by AFP, compared with 87 last year.

"Saudi Arabia has been on an execution spree in 2015, but beheading a child offender whose trial was unfair would be an appalling new low," Joe Stork, the deputy Middle East director of Human Rights Watch, said last week.

Despite widespread condemnation of Riyadh’s severe brand of justice, Saudi Arabia was recently named to head a key U.N. human rights panel — a decision that outraged rights activist throughout the world.

Speaking to the Associated Press this week, however, U.S. State Department spokesman Mark Toner said Washington had “human rights concerns” about Riyadh, a key regional ally, but that ultimately the U.S looked favorably on the appointment.

“We would welcome it,” Toner said. “We’re close allies.”

Al Jazeera and wire services