Hassan Firouzabadi, a senior military adviser to Iran’s supreme leader has died “of an illness,” the official IRNA news agency reported on Friday.

Firouzabadi served as the country’s highest-ranking military official after the supreme leader for nearly three decades despite having no military background.

IRNA did not elaborate on the exact cause of 70-year-old Hassan Firouzabadi’s death. Iran’s semi-official ISNA news agency reported that Firouzabadi died of COVID-19.

Firouzabadi was promoted to the rank of major general and appointed chief of staff of Iran’s armed forces in 1968 by Supreme Leader Ali Khamenei, making him the highest-ranking Iranian military official after the supreme leader, despite never serving in any of Iran’s military forces.

He retained that position until 2016, after which he was appointed by Khamenei as a senior adviser to the supreme leader.

He was also a member of the Expediency Council, which advises Khamenei. Firouzabadi was under EU sanctions for human rights abuses.