Iran's ex-President Akbar Hashemi Rafsanjani, a dominant figure in the country's politics since the 1980s, has died at the age of 82.
Mr Rafsanjani, president from 1989 to 1997, suffered a heart attack.
He played a pivotal role in the 1979 revolution but later in life became a counterpoint to hardline conservatives.
Supreme Leader Ali Khamenei hailed a "companion of struggle" despite their differences, saying that the loss was "difficult and overwhelming".
"The different opinions and interpretations at time in this long period could never entirely break up the friendship" between us, Ayatollah Khamenei said.
There will be three days of national mourning and a funeral in Tehran is due on Tuesday, which has been declared a public holiday.
Mr Rafsanjani was admitted to the Shohadaa Hospital in Tehran on Sunday, where doctors tried unsuccessfully for an hour to save him, media said.
A TV broadcaster broke into programmes to bring the news, saying Mr Rafsanjani "after a life full of restless efforts in the path of Islam and revolution, had departed for lofty heaven".