A Saudi court on Wednesday sentenced prominent Shiite cleric Nimr al-Nimr to death after convicting the anti-government protest leader of "sedition", his brother and lawyer said.
The verdict risks further escalating tensions with Saudi Arabia's minority Shiite community.
Nimr, a driving force behind 2011 protests against Saudi Arabia's Sunni authorities in the Eastern Province, was also convicted of seeking "foreign meddling" in the country, a reference to Iran, his brother Mohammed al-Nimr wrote on Twitter.
The court also found Nimr guilty of "disobeying" the kingdom's rulers and taking up arms against security forces, his brother said.
Nimr had been on trial since March 2013.
Most of Saudi Arabia's estimated two million Shiites live in the east, where the vast majority of the wealthy kingdom's oil reserves lie, and many complain of marginalisation.
They began demonstrating in February 2011 after an outbreak of violence between Shiite pilgrims and religious police in the Muslim holy city of Medina in western Saudi Arabia.
Protests escalated after the kingdom's intervention in neighbouring Bahrain to support that Shiite-majority country's Sunni monarchy.
Tension increased in July 2012 when security forces wounded and arrested Nimr.
Clashes have now killed about 24 people, including at least four policemen.