On Friday, the demonstrators chanted slogans against the Riyadh regime and called for the downfall of the ruling Al Saud monarchy in the Qatif region, situated about 418 kilometers (259 miles) east of the capital.
The incident came a day after the Saudi Interior Ministry warned the public against staging demonstrations in support of the prisoners in the kingdom and pledged to deal "firmly" with those participating in such protest rallies, press tv reported.
On October 8, hundreds of Saudi protesters also held a massive anti-regime rally in Qatif and shouted slogans against the Saudi authorities.
Since February 2011, Saudi protesters have held demonstrations on an almost regular basis in Eastern Provinces, mainly in the Qatif region and the town of Awamiyah, calling for the release of all political prisoners, freedom of expression and assembly, and an end to widespread discrimination.
However, the demonstrations have turned into protests against the Al Saud regime, especially since November 2011, when Saudi security forces killed five protesters and injured many others.
The Saudi interior ministry issued a statement on March 5, 2011, prohibiting "all forms of demonstrations, marches or protests, and calls for them".
The Saudi regime alleges that is has banned protests and demonstrations "because that contradicts the principles of the Islamic Sharia, the values and traditions of Saudi society, and results in disturbing public order and harming public and private interests".
In June, Saudi King Abdullah bin Abdulaziz Al Saud ordered the country's security forces to go on a state of high alert due to what he called a "turbulent situation" in the region.
According to Human Rights Watch, the Saudi regime "routinely represses expression critical of the government".