Saudi Arabia beheaded a convicted rapist and a murderer today, bringing to 37 the number of death sentences carried out in the kingdom this year.

Mohammed bin Ali bin Mohammed al-Bishi, a Saudi national, raped his victim at gunpoint, the interior ministry said in a statement carried by the official Saudi Press Agency.

"He also committed a number of armed robberies causing panic amongst the society. He had entered a number of homes by force and tried to kidnap and rape women and children," the statement said.

It added that Bishi was sentenced to death "as punishment and to serve as a deterrent to others".

Authorities carried out the sentence in the southwestern region of Asir.

In a separate case, Hamoud bin Salih bin Falih al-Zubi was executed in the capital Riyadh, the ministry said.

He was sentenced to death for gunning down a fellow Saudi during a brawl.

Drug trafficking, rape, murder, apostasy and armed robbery are all punishable by death under the Gulf kingdom's strict version of Islamic sharia law.

Amnesty International said in its annual report released last week that death sentences are often imposed "after unfair trials".

The London-based watchdog said some defendants claimed to have been tortured or "otherwise coerced or misled into making false confessions" before trial.

The kingdom executed 87 people last year, up from 78 in 2013, according to an AFP count.