Riyadh: A Saudi national convicted of murdering his father was beheaded on Thursday, bringing to 70 the number of executions carried out this year in the kingdom, the interior ministry said.

The number compares with 87 in the whole of 2014, according to an AFP tally.

Abdullah Al Balawi was convicted of stabbing his father to death, said a ministry statement carried by the official Saudi Press Agency. He was executed in the northwestern city of Tabuk.

SPA said the son had planned the murder but it did give his motives.

Amnesty International has criticised a "macabre spike" in the use of the death penalty this year in Saudi Arabia, which the London-based watchdog ranked among the top three executioners in the world in 2014.

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