A former top aide to the Jordanian king and a former envoy were found guilty of sedition on Monday and sentenced to 15 years in jail.
Officials said they had plotted to undermine the kingdom’s stability.
Bassem Awadallah, the former chief of the Royal Court and a close adviser to King Abdullah, and Sharif Hassan bin Zaid, a former envoy to Saudi Arabia, were convicted of “incitement against the ruling system” and “acts that could threaten society and create sedition”, said the sentence read out in the State Security Court.
The pair and 16 others were arrested in April and accused of working with foreign powers to undermine King Abdullah II and Jordan’s stability. The king’s half-brother, Prince Hamzah, was also implicated but was not arrested.
Awadallah and bin Zaid were handed 15-year sentences each, with hard labour for Awadallah. Bin Zaid was also found guilty of drug use and possession, Jordan’s state-run Al Mamlaka TV reported.
Both defendants pleaded not guilty to charges of sedition and incitement. Awadallah’s lawyer said he would appeal the verdict before the Court of Cassation.
State security court hearings in Jordan are closed to the media. The authorities said the pair were issued with “written accusations” related to fomenting instability.
Journalists outside the State Security Court were later shown short videos of the ruling being issued.
Images released by authorities showed the two men, in pale-blue prison uniforms, being escorted into the court on Monday by security staff wearing black.
The trial began on June 21.
Awadallah and Bin Zaid faced up to 20 years in prison if convicted of all charges.
The hashtag “Awadallah the Traitor” circulated on social media in Arabic on the morning of the trial.
Prince Hamzah, who was the crown prince of Jordan until 2004, was implicated in the plot but the royal family said it had resolved the matter internally.
The public rift within the monarchy was patched up when King Abdullah’s uncle, Prince Hassan bin Talal, urged Prince Hamzah to cease communication with alleged conspirators, stop making statements that harm the nation and repledge his loyalty to the kingdom. He had released videos accusing the government of corruption and of trying to silence him.
Days after Prince Hassan bin Talal resolved the dispute, King Abdullah and Prince Hamzah appeared alongside each other at an event to mark Jordan’s centenary.
The king appointed Hamzah as crown prince in 1999, at the request of his late father. But the king removed him from the post in 2004, later making his son, Prince Hussein, next in line to the throne.
The court rejected a defence request to summon Prince Hamzah and two other members of the royal family along with Prime Minister Bisher Al Khasawneh and Foreign Minister Ayman Safadi as witnesses, calling it “unproductive”.
US-educated Awadallah was long considered a contentious and divisive figure in Jordan, having served as finance and planning minister before becoming royal court chief in 2007.
He had pushed for economic reform before he resigned in 2008 and had been accused of interfering in sensitive political and economic matters.