(CNN) -- One of Saudi Arabia's most prominent and popular clerics has issued a stark warning to the Saudi government, saying it must take serious steps toward instituting reform, stamping out corruption and releasing political detainees "before violence is kindled."
In an open letter published online over the weekend, Salman Al-Oadah described a rising tide of anger in the deeply conservative kingdom, writing that "negative feelings have been accumulating for a long time" in Saudi Arabia.
"When tempers are high," added Al-Oadah, "religious, political and cultural symbols lose their value. The mob in the street takes control."
Al-Oadah, a conservative preacher who has more than 2 million followers on Twitter, was jailed from 1994 until 1999 as a result of his calls for political change and creation of an opposition group. His letter comes one week after two of Saudi Arabia's leading human rights activists were given lengthy jail sentences and at a time when the number of dissenting voices there has been growing.
Saudi Arabia, where protests are prohibited, never experienced the kind of unrest that took root in the region as a result of the Arab Spring. Yet small-scale demonstrations have become more and more frequent in the past several months. Protesters have repeatedly gathered to demand the release of jailed relatives they say have been held for years without having been charged, tried or given access to lawyers.
Al-Oadah addresses the issue of political prisoners extensively in his letter, writing that, "no one should be left in detention except for those who have clear and legitimate evidence brought against them."
Rights activists accuse Saudi Arabia's Interior Ministry of having detained thousands of citizens in connection with the country's counterterrorism efforts and say anger there is at an all-time high as a result.
Last month, 161 protesters were arrested in Buraidah outside the city's Bureau of Investigation and Prosecution. A police spokesman called the demonstration "an attempt to turn public opinion by taking advantage of those who have been accused and convicted of activities of the deviant groups." The term "deviant groups" is the language typically used by the Saudi government when referring to terrorist groups.
Just days earlier, dozens of women were arrested in the same city for staging a sit-in. Among their demands: the release of their relatives and the ouster of the country's interior minister, Prince Mohammed bin Nayef.
In one amateur video posted online, female protesters burned a picture of Prince Mohammed, a particularly brazen act in such an absolute monarchy -- one that Al-Oadah addresses in his letter.
"The recent burning of officials' pictures is a symbolic act that should give us some pause to think," writes Al-Oadah, "What got it started? Where is this all going?"
All in all, Al-Oadah paints a bleak picture of the situation in Saudi Arabia, writing that "causes of societal distress include: financial and administrative corruption, unemployment, inadequate housing, poverty, substandard health care and education, and dim prospects for political reform."