DUBAI Human Rights Watch and Amnesty International said Saudi Arabia had arrested two rights activists in the first ten days of this year and accused Riyadh of a crackdown on dissent.
The organisations said in press releases that Essam Koshak in Mecca and Ahmed al-Mushaikhass in the eastern city of Dammam were summoned for questioning by police last week but have yet to be released.
Koshak is being questioned about his tweets on human rights issues, Amnesty said, and al-Mushaikhass has advocated on behalf of relatives of detainees in the kingdom's Eastern Province - home to the Sunni Muslim-ruled country's Shi'ite minority.
"Saudi Arabia's relentless persecution of human rights defenders is a blatant campaign aimed at deterring them from speaking about the human rights situation in the country," said Lynn Maalouf of Amnesty.
A Saudi security spokesman did not immediately respond to a Reuters request for comment on the allegations.
The kingdom is a member of the 47-member United Nations Human Rights Council.
But it faced criticism last year by rights groups over a military campaign it leads in Yemen while a U.N. rights watchdog accused it of discriminating against girls and execution and corporal punishment of children.
Saudi Arabia has denied human rights abuses, saying it does not target civilians in Yemen and justifying punishments of minors based on its strict interpretation of Islamic law.
(Writing By Noah Browning; Editing by Sami Aboudi and Raissa Kasolowsky)