Saudi Arabia is waging a "systematic and ruthless campaign of persecution" against peaceful activists in order to silence criticism of the state in the wake of the 2011 Arab Spring uprisings, Amnesty International said Friday.

The rights group released a new 20-page report, titled "Saudi Arabia's ACPRA: How the kingdom silences its human rights activists," focusing mostly on the cases brought against 11 members of the Saudi Civil and Political Rights Association. Amnesty refers to the group as ACRPA, though it is also widely known by its Arabic acronym HASEM.

"The Saudi Arabian authorities have targeted the founding members of ACPRA one by one, in a relentless effort to dismantle the organization and silence its members, as part of a broader crackdown on independent activism and freedom of expression since 2011," the report said.

Amnesty said the government has also responded with force to protests for greater political rights, particularly those led by members of the country's Shiite minority. The rights group said that in other cases, security forces have used ill-treatment and torture against political detainees.

"The Saudi Arabian authorities have consolidated their iron grip on power through a systematic and ruthless campaign of persecution against peaceful activists in a bid to suppress any criticism of the state in the aftermath of the 2011 Arab uprisings," said Said Boumedouha, deputy head of Amnesty's Middle East and North Africa program.

Saudi officials have traditionally not responded to criticism from rights groups.

Eight out of the 11 main members of HASEM are detained, while the remaining three are free pending trial.

One of those detained is 24-year-old Umar al-Saeed, who was sentenced in December to four years in prison and 300 lashes. The verdict came in a secret, surprise session of his trial without his defense lawyers or family present.

Saudi Arabia is an absolute monarchy and all major decisions rest in the hands of King Abdullah, who is almost 90 years old. There is no elected parliament and little written law.

The kingdom aggressively monitors social media websites like Facebook and Twitter, where jokes about the aging monarchy are rife and where youth openly vent their anger over corruption and unemployment.

Human rights activists "play a vital role in a country that has no independent media, allows no independent political parties, has no legislature capable of holding the executive authorities to account, no independent judiciary, and where the authorities have made it a crime to 'communicate with external entities' such as Amnesty International," the report said.

Among the most common charges levied against critics is "breaking allegiance to and disobeying the ruler," said Amnesty International.

The kingdom this year passed a sweeping anti-terrorism law that criminalizes acts that disturb public order, defame the reputation of the state or threaten the kingdom's unity.

Saudi rights lawyer Waleed Abul-Khair, who helped found a group called Monitor of Human Rights in Saudi Arabia, was tried under the new law this year. He was sentenced to 15 years in prison and barred from traveling for another 15 years on charges related to his activism. He was found guilty of undermining the regime and officials, inciting public opinion and insulting the judiciary.

Abul-Khair and other activists have been tried by the kingdom's Specialized Criminal Court, which was established five years ago to try terrorism cases.

"We have now gone from being peaceful activists to being manufactured as terrorists by the government," HASEM activist Abdullah al-Shubaily, who will soon face trial over his activism, told The Associated Press. "We are being tried as terrorists and treated as terrorists."

Al-Shubaily said Saudi authorities have "criminalized free speech." He accused the government of turning a blind eye for years to Islamic extremists fighting abroad while clamping down on peaceful reformers. The kingdom this year made it illegal to fight in foreign conflicts.

Others also targeted since 2011 include two founding members of HASEM who are icons of the reform movement. Mohammed al-Qahtani and Abdullah al-Hamid were sentenced to 10-11 years in prison, with a five to 10-year ban on travel after that on charges of breaking allegiance with the ruler, inciting disorder, disseminating false information to foreign groups and founding an unlicensed organization.

The group was formed in 2009 to challenge the detention of people held for years without trial or beyond their sentences. Since then, it became one of the most vocal organizations in the kingdom, though it was never given a license. Unions and most independent civil society groups are not allowed to operate.

Earlier this year, at least 10 Saudis posted video statements on YouTube sharply criticizing the royal family and demanding change. At least three of those who appeared in videos were arrested, along with seven others connected to the videos.

Amnesty called on Saudi authorities to repeal the anti-terror law, release political prisoners, lift travel bans on activists and ensure all people are protected from torture and other ill-treatment.