The spiritual leader of Iraqi Shias, Grand Ayatollah Ali al-Sistani, suffered a heart attack in the holy Shia city of Najaf in southern Iraq, satellite Arabic TV network Al-Arabiya reports.
The 80-year-old cleric was admitted to hospital, where was under observation, Al-Arabiya said. Poor health has forced him to gave up teaching at Najaf's Islamic University, AKI reported.
Al-Sistani is revered by Iraqi Shias who consider him the highest authority in Shia Islam.