A report by New York-based Human Rights Watch (HRW) on Thursday said unfavorable treatment of Shiite Muslims "extends from education and employment to the justice system."
Based on the report, Shiite Muslims have been arrested and their prayer halls have been shut down since a group of Shiite pilgrims clashed with monarch's religious police in the holy city of Medina in February 2009, press tv reported.
Several Shiite Muslims were reportedly killed and dozens others were detained by the Kingdom security forces in the incident which drew international condemnations against the monarch system.
Human Rights Watch said some of the Shiite followers arrested were detained for as much as a month without trial.
Also the group said that Shiite protesters faced arbitrary arrests in the Kingdom's Eastern Provinces in March as well.
Several Shiite community members and religious leaders have been detained in recent months, according to the group. The community members also complain they are not allowed to have their own mosques in Saudi Arabia
The report comes at a time when a Shiite dissident, Hadi al-Mutif, who has been on death row in Saudi Arabia for 16 years, was sentenced this week to another five years in jail.
The verdict issued on Monday punished Hadi for criticizing the monarch justice system.
Shiite Muslims have long complained of being treated as second-class citizens in the kingdom. They comprise nearly one-fourth of the Saudi population.
Human Rights Watch's Middle East and North Africa director said the increased tensions surrounding the minority population highlight a need for equal rights for Shiite residents of Saudi Arabia.
"All the Saudi (Shiites) want is for their government to respect their identity and treat them equally," Sarah Leah Whitson said in a statement.
"Yet Saudi authorities routinely treat these people with scorn and suspicion."
Zeidi Shiites in Yemen have also accused Saudi Arabia and al-Qaeda of helping the Yemeni government in its crackdown on them.
Yahya al-Houthi, a dissident Yemeni lawmaker, blamed Riyadh for propagating Wahhabi ideology in Yemen and for using his country as a base for terrorism.
"In recent months [Yemeni President] Ali Abdullah Saleh has taken many recruits of al-Qaeda who were afraid of falling into the hands of their regimes in countries like Egypt, Somalia, Pakistan and Afghanistan. His plan was to use these fighters from al-Qaeda to battle the Houthis in Saada," al-Houthi told Press TV on Saturday.