A Saudi court jailed five people for up to 30 years on charges including plotting to blow up an oil refinery on behalf of al-Qaeda.
The official SPA news agency gave no details of when the alleged plot against the refinery in the Red Sea port of Yanbu took place.
But the trial is believed to be the latest in a series of prosecutions begun in July 2011 for alleged offences committed during the peak of al-Qaeda violence in the kingdom between 2003 and 2006.
SPA reported that the court found that some of the defendants had "plotted to blow up the Yanbu oil refinery and participated in preparing car bombs to that end", adding "some have joined Al-Qaeda and are linked to its most dangerous leaderships".
The court didn't pass sentence in Sunday's hearing against two other defendants who were not brought to the hearing, SPA reported, without elaborating if they were tried in absentia. Other defendants were convicted of lesser arms possession charges and received shorter jail terms, one of just five months.