Iranian opposition leader Mir Hossein Musavi has been transferred to house arrest, a day after he was hospitalized due to heart problems.

The opposition website Kalame, which is close to Musavi, reports that the opposition figure underwent a heart procedure before being sent home where he’s been held under arrest since February 2011.

One of Musavi’s daughters, who had met with him, wrote on Twitter that her father’s heart is still in serious “danger.”

According to “Kalame,” doctors had demanded urgent treatment for Musavi several months ago but officials did not allow it.

Musavi along with his wife and fellow reformist cleric Mehdi Karrubi were put under house arrest after their call for a protest in solidarity with the uprisings in several Arab countries attracted thousands of protesters.

Musavi and Karrubi accused Iranian authorities of massive vote rigging in the 2009 presidential vote.

RFE/RL