The son of Mehdi Karroubi, who has been under house arrest since early 2011, told Radio Farda that his father has been hospitalized for heart problems.
Mohammad Taghi Karroubi said that a doctor from the Intelligence Ministry had examined his father on Monday and ordered his hospitalization.
Mehdi Karroubi was one of the two presidential candidates who ran against Mahmoud Ahmadinejad in the 2009 presidential elections, which ended in an unprecedented upheaval, costing the lives of dozens of protesters and the imprisonment of hundreds.
Ali Motahari, the outspoken Deputy Parliament Speaker tweeted on Tuesday that Mr. Karroubi's illness is an opportunity to use wisdom and end his house arrest.
Mr. Motahari in a June 2 letter to the head of Iran's Judiciary had asked for the house detention to end. He has also criticized the detention of of 2009 presidential candidates on other occasions.
Mr. Karroubi junior told Radio Farda that his father’s heart problems are a result of his detention and six years of house arrest. His latest discomfort started on Saturday night.
He was hospitalized briefly on March 5 when he underwent heart examination and returned home.
Mohammad Taghi Karroubi also insisted that since his detention, his father “has undergone six operations, while before [detention] he was in good physical condition”.
The operations he was referring to related to various ailments, including a heart operation.
Mehdi Karroubi, along with Mir-Hossein Mousavi and his wife Zahra Rahnavard have been under house arrest since January 2011. Now, considered opposition leaders, the detainees and specially Mr. Mousavi are regarded as leaders of the Green Movement, which demanded the reversal of the 2009 official election result.
Mr. Karroubi is a former speaker of parliament and Mr. Mousavi a former prime minister.
They have not been charged with any crime, and it is generally believed that their continued detention is a decision made at the very top of Iran’s leadership.
The Judiciary, which is loyal to the Supreme Leader Ali Khamenei, insists that the decision to keep the three dissidents under house arrest was made by the Supreme National Security Council.
President Hassan Rouhani, who chairs the Security Council has denied such a decision.