BRUSSELS (Reuters) - The European Union's foreign policy chief warned on Saturday that Saudi Arabia's execution of a prominent Shi'ite Muslim cleric risked "dangerous consequences" by further inflaming sectarian tensions in the region.

The kingdom executed cleric Nimr al-Nimr on Saturday alongside dozens of al Qaeda members, signaling that it would not tolerate attacks, whether by Sunni jihadists or from its Shi'ite minority.

EU foreign policy chief Federica Mogherini, reiterating the bloc's opposition to the death penalty and mass executions in particular, said Nimr's case raised serious concerns over freedom of expression and the respect of basic civil and political rights in Saudi Arabia.

"This case has also the potential of inflaming further the sectarian tensions that already bring so much damage to the entire region, with dangerous consequences," she said, urging Saudi authorities to promote reconciliation between different communities in the country.

(Reporting By Philip Blenkinsop; Editing by Kevin Liffey)