Jordan's Prince Hamzah hoped to overthrow King Abdullah II with the backing of Saudi Arabia, according to court indictments against two alleged accomplices released Sunday.

Both the accused have close ties to neighbouring Saudi Arabia: former royal court chief Bassem Awadallah, who also holds Saudi nationality, and former special envoy to the kingdom, Sharif Hassan bin Zaid.

The two men face trial at the State Security Court later this month, and face up to 20 years in prison if found guilty, according to one of their lawyers.

But Hamzah, the king's half-brother, who was accused of involvement in the alleged April 3 attempt to "destabilise the kingdom's security", will not stand trial.

Authorities have said his case had been resolved within the Hashemite royal family.

Regional powerhouse Saudi Arabia has fervently denied any involvement in the alleged plot.

After the news first broke, Riyadh quickly expressed "its full support" for Jordan "and for the decisions and measures taken by King Abdullah II and Crown Prince Hussein to safeguard security and stability".

But while Hamzah, the king's half-brother, will not face trial, his alleged role will be central to the trial.

"Prince Hamzah was determined to satisfy his personal ambition to rule, in violation of the constitution and Hashemite custom," the indictment read.

"To succeed, he sought to exploit the concerns and problems of the population and to arouse sedition and frustration in society," it added.

Awadallah is considered by several Jordanian media outlets to be close to Saudi Crown Prince Mohamed bin Salman.

The indictment said Awadallah was "close to officials of the kingdom of Saudi Arabia" and had a network of contacts abroad.

Hamzah was reportedly especially concerned about Riyadh's attitude.

"If something bad happens to me in Jordan, will Saudi officials help me or not?" Hamzah reportedly asked Awadallah, according to the indictment.