Saudi Arabia executed a Syrian murder convict on Tuesday, bringing to 87 the number of people put to death in the conservative kingdom this year.

Ahmed al-Ramadan was found guilty of stabbing and strangling to death a Saudi as the victim was leaving his home for dawn prayers, the interior ministry said, without specifying their relationship.

Authorities carried out the death sentence in the Qassim region, northwest of Riyadh.

Most people put to death in Saudi Arabia are beheaded with a sword.

The executions so far this year include 47 for "terrorism" carried out in a single day on January 2.

Murder and drug trafficking cases account for the majority of Saudi executions.

Amnesty International said Saudi Arabia had the third highest number of people put to death last year, at least 158.

That was far behind Pakistan, which put to death 326 people, and Saudi Arabia's regional rival Iran, which executed at least 977, said Amnesty, whose figures exclude secretive China.