Story highlights One man sentenced to a decade in prison for posting pro-protest messages to Twitter

A second man got eight years, convicted of insulting Saudi Arabia's king via Twitter

Critics say it's all part of the kingdom's efforts to quash dissent

Two men were found guilty in Saudi courts this week for, among other offenses, messages they posted on Twitter.

On Monday, one Saudi man was sentenced to 10 years in prison for using Twitter to encourage protests and undermine the country's leadership, according to Saudi Arabian state news agency SPA.

"The accused had sent invitations via Twitter to participate in protests and gatherings against the Kingdom," read SPA's statement, quoting Saudi Justice Ministry spokesman Fahad Al-Bakran.

Al-Bakran added how the unnamed man, already serving a three-year jail sentence, was convicted of utilizing websites that are "hostile to the government and that promote deviant ideologies." Saudi officials often use the phrase "deviant ideologies" when describing al Qaeda or al Qaeda-linked groups.

On Sunday, another man, accused of insulting King Abdullah and inciting protests via social media sites like Twitter, was sentenced to eight years in jail.

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According to SPA, he's also barred from travel and from posting messages on social media sites for eight years after his release.

The man, also unidentified by SPA, was found guilty of "inciting relatives of Saudis arrested for security reasons to protest their imprisonment by tweeting and via posting videos on sites like YouTube."

Al-Bakran added the man had been arrested once before for similar offenses, but was released after signing a pledge never to do so again.

Both sentences come just days after Saudi Arabia officially declared the Muslim Brotherhood to be a terrorist organization.

On Friday, the country's Interior Ministry announced that the Brotherhood, as well as the Islamic State of Iraq and Syria (ISIS), Al-Nusra Front and other groups had been formally designated terrorist organizations.

The statement also detailed the country's new, comprehensive anti-terror legislation, warning any Saudi or foreigner residing in Saudi Arabia they could be sentenced to heavy jail terms for joining extremist groups or fighting alongside them.

Many, however, maintain the new laws are a barely disguised effort to quash dissent, pointing to the fact that Friday's Interior Ministry statement also criminalized atheism, more specifically, any Saudi or resident of Saudi Arabia "propagating atheist ideologies by any means, or questioning the principles of Islamic faith."

"It's unfortunate that the statement comingles the (Saudi) government's ongoing intent to severely limit freedoms of expression and religion with its efforts to counter extremism and terrorism," said Dwight Bashir, deputy director for policy and research with the United States Commission on International Religious Freedom.

"It reinforces longstanding concerns that the Saudis will spare no expense to crush dissent," Bashir told CNN, "and punish non-conforming views, even if the views are protected by internationally-recognized human rights."

Bashir called the move to criminalize atheism "very troubling," adding it was "consistent with the way the Saudis masquerade 'insults to religious feelings' as a way of garnering support for other laws that seek to counter religious extremism and name specific entities as terror groups."

Saudi Arabia, which has jailed several prominent reform activists in the past two years, is consistently singled out and criticized for its human rights record.

In a statement from late February, Adam Coogle, a Saudi researcher for Human Rights Watch, wrote the new anti-terror legislation has "created a veneer of legality for ongoing human rights abuses by Saudi criminal justice authorities."

"The terrorism law," added Coogle, "is a vague, catch-all document that can -- and probably will -- be used to prosecute or jail anyone who criticizes the Saudi government and to violate their due process rights along the way."