A former leader of the Palestinian Islamic Jihad militant group Ramadan Shallah has died after battling illness, Al Manar TV reported on Saturday.
Shallah, 62, served as secretary general of the Iran-backed group from 1995 to 2018.
Al Manar did not specify the exact nature of the illness.
Labelled a terrorist organisation by the United States, European Union and others, the group has waged attacks on Israel and aims to establish an Islamic Palestinian state.
"By losing Shallah we lost a great national man," said Palestinian President Mahmoud Abbas in a statement published by the Palestinian official news agency WAFA.
Shallah was born in Gaza in 1958 and studied in Egypt before earning a PhD in economics in the United Kingdom.
He was elected head of Palestinian Islamic Jihad after the killing of the group's former chief, Fathi Shiqaqi, in 1995.
Palestinian Islamic Jihad has offices in Syria and Lebanon, but most of its activities are focused in the Palestinian enclave of the Gaza Strip. Mosque loudspeakers across Gaza blared in the evening with tributes to Shalah.
Last year, the movement took part in several rounds of heavy fighting with Israel. But in recent months it has remained committed to an unofficial truce brokered by regional mediators between Israel and Hamas, the larger Islamic group ruling Gaza.
Palestinian Islamic Jihad previously has taken part in numerous suicide bombings, shootings and rocket attacks that killed dozens of Israelis.
Shalah was on the US "most wanted list" of terrorist suspects with a $5 million reward for information leading to his arrest or conviction.
