AMMAN, July 12 (Reuters) - A Jordanian court on Monday sentenced a former royal chief adviser, Bassem Awadallah, and a minor royal to 15 years in jail for their involvement in an alleged plot to bring a deposed crown prince to power instead of the king. The military court said it had confirmed evidence backing the charges against the pair and that they had both been determined to harm the monarchy by pushing former heir to the throne Prince Hamza as an alternative to King Abdullah. "The two defendants held views that are against the political system and the monarchy and sought to create chaos and sedition in Jordanian society," said the judge. Awadallah, a former finance minister who was a driving force behind Jordan"s liberal economic reforms, was charged with agitating to undermine the political system and committing acts that threaten public security and sowing sedition. A handcuffed, distraught looking Awadallah in a blue prison outfit was led to court by several elite anti-terror squad members for the sentencing on Monday, a leaked video posted on social media showed. The 57-year-old Western educated economist, whose closeness to the monarch over many years had enraged a conservative political establishment that holds power within the army and security forces, was once praised by King Abdullah for "his distinguished service to his country." He was forced to resign as royal court chief in 2008 after lobbying by an old guard of politicians and influential tribal figures opposed to his free market reforms. Awadallah pleaded not guilty in the secretly held trial, which his lawyer, former U.S. federal prosecutor Michael Sullivan, said had not been fair and lacked due process. "The so-called trial was conducted by a secret military court where he was denied the opportunity to refute any of the prosecution’s evidence and he was not allowed to call witnesses who would provide exculpatory evidence on his behalf," Sullivan said in a statement sent to Reuters. He said there had been "absolute denial of any transparency in the tribunal proceedings, and the inhumane treatment, including beatings and psychological torture." Awadallah"s family has also alleged he was tortured and said his confession was extracted under duress. Jordan"s public prosecutions office has said Awadallah was at no point threatened or tortured, nor did he make his testimony under coercion. The Jordanian defence team said they would appeal the decision. ALLEGIANCE The estranged Prince Hamza, who had been placed under house arrest earlier this year, has avoided punishment and defused the crisis last April by pledging allegiance to the king. The court backed the validity of evidence presented by the prosecution based on intercepted internet messages. Awadallah, a Jordanian of Palestinian origin drawn from outside the traditional palace entourage, allegedly advised Hamza on critical tweets the prince wanted to send to further his ambitions. Authorities say the messages are irrefutable evidence of how Hamza was exploiting popular anger against the state. They say the suspects prodded Hamza to step up his agitation among disgruntled members of powerful tribes that traditionally support the monarchy. Hamza"s supporters describe the leaks as character assassination. (This story corrects former role of lawyer to federal prosecutor from district attorney in paragraph 8)