Iranians turned out to mourn Hamas political leader Ismail Haniyeh on Thursday, a day after he was assassinated in Iran's capital in an attack that has heightened fears of a direct conflict between Tehran and Israel.
State TV broadcast live images of Supreme Leader Ayatollah Ali Khamenei leading prayers at Haniyeh's funeral at Tehran University, where thousands of mourners dressed in black chanted "Death to Israel" and "Death to America".
His body will be flown to Qatar, where Haniyeh was usually based, for burial on Friday.
"Rest in peace, Abu Al-Abed Ismail Haniyeh. Our nation, Iran, the Axis of Resistance, your people, your fighters ... are united in the choice of resistance to end the Zionist occupation," said Hamas deputy chief in Gaza Khalil Al-Hayya in a televised speech at Tehran University.
The Axis of Resistance is an alliance built over four decades of Iranian support to resist Israeli and US influence in the Middle East.
Iran and the Palestinian Islamist militant group have accused Israel of carrying out the strike that killed Haniyeh hours after he attended the inauguration of Iran's new president in Tehran on Wednesday.
But Israeli officials have not claimed responsibility for the attack that drew threats of revenge on Israel and fuelled further concern that the Israel-Hamas conflict in Gaza was turning into an all-out war in the Middle East.
Hamas' armed wing has said in a statement Haniyeh's killing would "take the battle to new dimensions and have major repercussions". Vowing to retaliate, Iran declared three days of national mourning on Wednesday and said the US bore responsibility because of its support for Israel.
"All fronts of the resistance will take revenge for Haniyeh's blood," Ali Akbar Ahmadian, the secretary of Iran's Supreme National Security Council, told Iran's semi-official Mehr news agency. .
The Axis includes Hamas, the Palestinian group that ignited the war in Gaza by attacking Israel on Octover 7, the Hezbollah movement in Lebanon, the Houthi movement in Yemen and various Shi'ite armed groups in Iraq and Syria.
The region faces a risk of widened conflict between Israel, Iran and its proxies after Haniyeh's assassination and the killing of Hezbollah's senior commander on Tuesday in an Israeli strike on the outskirts of the Lebanese capital Beirut.
On April 13, Iran launched a barrage of missiles and drones at Israel in what it said was retaliation for Israel's suspected deadly strike on its embassy compound in Damascus on April 1, but almost all were shot down.
"We want revenge because Israel killed Haniyeh, who was our guest," an Iranian woman, who attended a rally after the ceremony at Tehran University, told state TV.