Protesters held placards to demonstrate against the execution of prominent Shi'ite cleric Sheikh Nimr al-Nimr outside the Saudi Arabian embassy in London on Saturday.
Saudi Arabia executed Nimr and dozens of al Qaeda members on Saturday, signaling that it would not tolerate attacks, whether by Sunni jihadists or minority Shi'ites, and stirring sectarian anger across the region.
Nimr, the most vocal critic of the dynasty among the Shi'ite minority, had come to be seen as a leader of the sect's younger activists, who rejected the quiet approach of older community leaders for failing to achieve equality with Sunnis.