Saudi Arabia put four people to death on Thursday, bringing to 100 the number of executions since the start of the year, according to an AFP tally based on official statements.

The latest executions reported by the official Saudi Press Agency come amid fresh condemnation of the kingdom's human rights record after 81 people were put to death in a single day last week.

Of the 100 executions, three on Wednesday coincided with a visit by British Prime Minister Boris Johnson, who was in Riyadh to lobby for a rise in oil output to help stabilise markets following Russia's invasion of Ukraine.

On Saturday, Saudi Arabia's execution of 81 people in one day -- on various charges, including terrorism-related offences -- exceeded the total of 69 killed in the whole of 2021.

Human Rights Watch said it was "highly unlikely" that the 81 men received fair trials, calling it a "brutal show of its autocratic rule".

More than half of them, 41, belonged to the kingdom's Shiite Muslim minority "who have long suffered systemic discrimination and violence by the government", the New York-based rights group said.

Saudi Arabia said the men, who included seven Yemenis and one Syrian, belonged either to the ISIS group, Al-Qaeda, Yemen's Huthi rebels or "other terrorist organisations".