“We in Hamas mourn the passing of Ayatollah Ali Khamenei. He provided all forms of political, diplomatic and military support to our people, our cause, and our resistance,” the Palestinian Islamist movement said in a statement.

“The US and the fascist occupation government bear full responsibility for this blatant aggression and heinous crime against the sovereignty of the Islamic Republic of Iran, as well as for its serious repercussions on the security and stability of the region.”

Hamas’ armed wing, the Ezzedine Al-Qassam Brigades, described Khamenei as the “main supporter of the Resistance Axis and its mujahideen”.

“All the support the Islamic Republic has provided over decades to our people and our resistance … was delivered by his direct decision and under his full supervision,” the Brigades said in a separate statement.

“This substantial support has been a key factor in the development of the resistance and its tactics, culminating in the remarkable achievements” during the Oct 7, 2023, attack on Israel, the group added.

Militant group Islamic Jihad, which along with Hamas and its armed wing fought a war against Israel in Gaza for two years, said the killing of Khamenei was a “war crime” by the US and Israel in a “treacherous and malicious attack”.