Iran's opposition leader Mir Hossein Musavi has been hospitalized due to heart problems, the opposition website Kalame reports.
One of Musavi's daughters confirmed the report on social media.
Musavi is said to have been transferred to the coronary unit of a Tehran hospital that specializes in cardiology on April 29.
Musavi, who along with his wife has been under house arrest since February 2011, has been reportedly suffering from a heart condition.
Kalame says the opposition figure has been in need of a cardio procedure for the past several months.
Musavi was also taken to the hospital for tests and treatment during the last year.
Musavi and reformist cleric Mehdi Karrubi, who is also under house arrest, accused Iranian officials of vote rigging in the 2009 presidential vote.
Reported by Golnaz Esfandiari in Washington