Iran's supreme leader has blasted as "foolishness" a decision by Bahrain's leaders to strip a top Shia Muslim cleric of his citizenship, and said it could provoke violence from Shias.

The speech by Ayatollah Ali Khamenei, carried by state media, came after Bahrain's Sunni authorities stepped up measures against the island island's Shias and stripped their spiritual leader, Ayatollah Isa Qassim, of his citizenship.
"This is blatant foolishness and insanity. When he still could address the Bahraini people, Sheikh Isa Qassim... would advise against radical and armed actions," Khamenei said in remarks carried by state television on Sunday.
"Attacking Sheikh Isa Qassim means removing all obstacles blocking heroic Bahraini youths from attacking the regime."
Bahrain in 2011 put down an uprising led by Shias demanding reforms. Since then, there have been almost daily skirmishes between Shia youths and security forces, as well as several bomb attacks.
Bahrain accuses Iran of fomenting unrest among its Shia population and providing financial and material support, a charge Tehran denies.
In a series of moves over the past three weeks, authorities also closed down the main Shia opposition al-Wefaq Islamic Society, doubled the prison sentence on the group's leader, Sheikh Ali Salman, and detained prominent rights campaigner Nabeel Rajab.