Saudi Arabia has put 32 people on trial, including 30 members of its own Shi'ite Muslim minority, accused of spying for Iran, several local newspapers and television reported on Monday.
The 32, including an Iranian and an Afghan, were detained in 2013 sparking expressions of concern among Saudi Shi'ites who said that several were well known figures in their community and not involved in politics.
The trial is the first in recent memory for Saudis accused of spying and may stoke tensions between local Shi'ite and Sunni Muslims and with Iran, which strongly denied the accusations at the time.
The bitter rivalry between the Sunni-ruled kingdom and Iran, a Shi'ite theocracy, has aggravated wars and political struggles in Syria, Iraq, Lebanon, Yemen and Bahrain and is regarded by many analysts as a cause of regional instability.
Tensions escalated further in January when Riyadh broke off diplomatic ties following the storming of its Tehran embassy by protesters angered at Saudi Arabia's execution of a Shi'ite cleric convicted of involvement in the killing of policemen.
Riyadh's Bureau of Public Prosecution presented the charges against the 32 on Sunday at the Specialized Criminal Court, which tries security offenses, the Saudi-owned al-Arabiya channel reported.