The Islamic State terror group has claimed responsibility for the attacks that killed almost 100 people in the southern city of Kerman in Iran.
The group made the claim on Telegram and said two suicide bombers were involved in the attack on Wednesday.
Experts who follow the group confirmed the statement, circulated online among jihadists, came from the extremists, who likely hope to take advantage of the chaos gripping the region amid Israel's war on Hamas in the Gaza Strip.
It comes after Iranian leaders vowed revenge for the two explosions at a ceremony to commemorate Revolutionary Guards commander Qassem Soleimani on the anniversary of his death.
"A very strong retaliation will be handed to them on the hands of the soldiers of Soleimani," First Vice President Mohammad Mokhber told reporters at a hospital were some of the wounded from Wednesday's blasts were receiving treatment.
The UN Security Council condemned the attacks and Iranian authorities have called for mass protests on Friday, when the funerals of the victims' of twin blasts will be held, state media reported.
Its Revolutionary Guards Corps described the attacks as a cowardly act "aimed at creating insecurity and seeking revenge against the nation's deep love and devotion to the Islamic Republic".Wednesday's attack in Kerman killed at least 84 people and wounded another 284.
It targeted a ceremony honoring Soleimani, held as an icon by supporters of the country's theocracy and viewed by the US military as a deadly foe who aided militants who killed American troops in Iraq.
Local media quoted a government official as saying surveillance footage from the route to the commemoration at Kerman's Matryrs Cemetery clearly showed a male suicide bomber detonating explosives. An earlier death toll of 103 was twice revised lower after officials realised that some names had been repeated on a list of victims and due to the severity of wounds suffered by some of the dead, health authorities said.
Many of the wounded were in critical condition, however, so the death toll could rise.
The attacks came a day after a deputy head of the Palestinian militant group Hamas was killed in a suspected Israeli strike in Beirut.Iran has multiple foes who could be behind the assault, including exile groups, militant organisations and state actors.
Sunni extremist groups including Islamic State have conducted large-scale attacks in the past that killed civilians in Shiite-majority Iran, though not in relatively peaceful Kerman.Iran also has seen mass protests in recent years, including those over the death of 22-year-old Mahsa Amini in 2022.
The country also has been targeted by exile groups in attacks dating back to the turmoil surrounding its 1979 Islamic Revolution.
