Saudi Arabia will no longer impose a death sentence on individuals who committed crimes while still minors, the state-backed Human Rights Commission (HRC) said in a statement, citing a royal decree by King Salman.

"The decree means that any individuals who received a death sentence for crimes committed while he or she is a minor can no longer face execution. Instead, the individual will receive a prison sentence of no longer than 10 years in a juvenile detention facility," HRC President Awwad Alawwad said in the statement.

It was not immediately clear when the decree, which was not immediately carried on state media, would take effect.

Saudi Arabia, whose human rights record came under intense international scrutiny after the murder of a prominent Saudi journalist in 2018, is one of the world's biggest executioners after Iran and China, Amnesty International said in its latest annual report.

It said the kingdom had executed 184 people in 2019, including at least one person charged with a crime committed as a minor.

"This is an important day for Saudi Arabia," Alawwad said. "The decree helps us in establishing a more modern penal code, and demonstrates the kingdom’s commitment to following through on key reforms across all sectors of our country."

The announcement came just two days after the kingdom in effect scrapped the punishment of flogging, in a decision by the General Commission for the Supreme Court. The punishment will instead be replaced by prison time or fines.

Capital punishment for crimes committed by people under the age of 18 runs contrary to the UN Convention on the Rights of the Child, which Saudi Arabia has ratified.

In April 2019, the Sunni-ruled kingdom beheaded 37 men convicted of terrorism charges. The UN human rights chief said at the time that most of them were Shi'ites who may not have had fair trials and at least three were minors when sentenced.

Crown Prince Mohammed bin Salman has launched a series of social and economic reforms aimed at modernising the conservative kingdom, which has no codified system of law to go with the texts making up sharia, or Islamic law.