Dozens of people wearing white shrouds have staged a peaceful march in the oil-producing region of eastern Saudi Arabia, demanding basic rights and the release of prisoners, according to a video posted on YouTube.
The video recording, dated June 24, showed some 30 men, many in Western clothes, marching with white shrouds that symbolise willingness to die as martyrs, in the mainly Shi'ite city of Qatif on Friday.
It was not immediately possible to verify the authenticity of the recording, but Shi'ites have often held small protests in the area.
A Saudi interior ministry spokesman said he was not aware of the report but would check with local police.
A local rights activist said the protest, inspired by a government crackdown on fellow Shi'ites in neighbouring Bahrain, was the first one of its kind in the area in two months.
"The demonstrators were not calling for bringing down the regime. They were simply demanding basic rights and an end to sectarian discrimination," Mohammed al-Said said by telephone.
He said activists from the Shi'ite minority in the area had suspended protests in April following government promises to start a dialogue with them and free detainees.
Sunni-Muslim-ruled Saudi Arabia, the world's top oil exporter and a major US ally, does not tolerate any form of public dissent. Scattered protests have been held in the past in eastern Saudi Arabia, where mostly Shi'ite Muslims live.
Although the demonstrators had concealed their faces with checkered grey or black traditional Arab headscarves, the footage was mostly filmed from the back, apparently as extra security to prevent authorities from identifying the protesters.
Some of the demonstrators had inscribed the text of Article 9 of the Universal Declaration of Human Rights on their backs.
"No one shall be subjected to arbitrary arrest, detention or exile," read the red text, written in bold Arabic letters.
The demonstrators also voiced solidarity with activists in Bahrain, facing a continuing crackdown from the government after protests were crushed in March.
Saudi Arabia, unnerved by Bahrain's uprising, had sent in troops after the small kingdom asked Gulf neighbours to support its crackdown.
"Saudi army out, Bahrain is free," the protesters in Qatif chanted.
A separate and smaller night protest dated June 22 was posted on YouTube, showing a handful of young men marching in the town of Awwamiya while chanting "God is Greatest".
Activists also released still pictures of a separate protest by veiled women in full black garb, who also donned white shrouds on their backs to symbolise martyrdom marching in eastern Saudi Arabia.
"We demand the release of prisoners forgotten (for) 16 years)," one placard in red and blue read.
"We will take all paths, and will not shy away from our prisoners, rights," another placard read.