People mourn beside the coffin of Iran's influential cleric politician Akbar Hashemi Rafsanjani inside Jamaran mosque in northern Tehran, capital of Iran, on Jan. 8, 2017. [Photo/Xinhua]

TEHRAN - Iran's influential cleric politician Akbar Hashemi Rafsanjani died of heart disease on Sunday.

Rafsanjani, 82, was hospitalized on Sunday due to a heart attack, but the medication attempts were not successful, local reports said.

In his message on Sunday, Iran's Supreme Leader Ayatollah Ali Khamenei expressed grief over the sudden demise of an old friend, fellow and ally during the 1979 Islamic revolution and close colleague during the post-Islamic revolution period, according to Press TV.

Khamenei said that Rafsanjani's loss is overwhelming and very hard to bear as he was a reliable support for the leadership of the country.

On Rafsanjani's demise, President Hassan Rouhani's administration announced three mourning days. The announcement also said that all the governmental institutions would be closed on Tuesday for the funeral ceremony.

Born in August 1934 in Iran's Bahreman, Rafsanjani was an influential politician, religious scholar and the confidant of Ayatollah Ruhollah Moosavi Khomeini, the late founder of the Islamic Republic of Iran.