Ayatollah Ali al-Sistani, Iraq's most influential Shia cleric who has been a voice for moderation, has successfully undergone heart surgery in London, an aide said on Saturday.
"The Ayatollah had an operation to unblock a coronary artery on Friday. His condition is stable," a representative from Sistani's office told Reuters.
He said there was no indication when the 73-year-old Muslim cleric would be well enough to leave hospital or when he would return to Iraq.