New details have emerged about the assassination of Hamas political bureau chief Ismail Haniyeh in Tehran last Wednesday.

Two Iranian officials told the British newspaper, The Telegraph, that the Mossad's main plan was to assassinate Haniyeh during the funeral of Ebrahim Raisi, who died along with his foreign minister and his companions after his helicopter crashed in the northwestern Azerbaijan province of the country last May.

They explained that Mossad changed the plan to assassinate Haniyeh during Raisi's funeral due to the possibility of it failing due to the large crowds.

For his part, a Revolutionary Guard official announced that additional explosive devices were found in the building where Haniyeh was assassinated, according to the Telegraph.

He also said that Mossad hired Iranian security agents to place the explosive device in Haniyeh's room.

He explained that explosive devices were placed in three rooms in the guest house in Tehran where the Hamas leader was staying, and then detonated remotely from outside.

The Revolutionary Guards official said that Mossad used Iranian security personnel from the Ansar al-Mahdi unit in the assassination, referring to the Iranian Revolutionary Guards unit responsible for the safety of high-ranking officials.

The agents were seen moving stealthily in and out of several rooms within minutes, according to officials who have surveillance camera footage of the building.

The newspaper reported that the agents had infiltrated the country, but their source was still in Iran.

A second official in the elite military forces of the Iranian Revolutionary Guard considered the assassination of the head of the political bureau of Hamas in Tehran a humiliation for Iran and a major security breach.

The official revealed that a working group had been formed to come up with ideas to portray the assassination as not a security breach.

For his part, a person close to Iranian President Masoud Pezeshkian said that the security breach may have been intentional by the Revolutionary Guards to harm the president.

"The Revolutionary Guards are not satisfied with some of the Iranian president's policies," he added.

The two Iranian officials said that Supreme Leader Ali Khamenei is more interested in knowing the reasons for the security breach than the reason for revenge.

The Iranian Fars News Agency, affiliated with the Revolutionary Guards, reported on Thursday that investigations proved Tel Aviv's responsibility for planning and executing the assassination of Haniyeh.

She also said that "Haniyeh's room was on the fourth floor of the guest house in the Zaafaraniya area."

The Iranian agency also stated that Haniyeh's room was hit by a projectile, which led to the destruction of parts of the ceiling and windows of his residence, killing him and one of his guards.

The guesthouse is run and protected by the Islamic Revolutionary Guard Corps and is part of a large complex known as Nishat, in an upscale neighborhood in northern Tehran.

Israel has not publicly acknowledged responsibility for the killing, but Israeli intelligence officials briefed the United States and other Western governments on the details of the operation in the immediate aftermath, the New York Times reported.

Seven officials revealed to the American newspaper that an explosive device that was secretly smuggled into the guest house in Tehran where he was staying was what led to Haniyeh's death.

Officials added that the bomb was detonated remotely once he was inside his guesthouse room. The explosion also killed a bodyguard, according to the New York Times.

Two sources familiar with the assassination of Hamas political bureau chief Ismail Haniyeh confirmed that the Israeli Mossad assassinated Haniyeh by detonating an explosive device that had been planted in advance in his bedroom at the official Iranian government residence in Tehran.

The sources said that Israeli intelligence knew which facility and which room exactly Haniyeh stayed in during his visits to Tehran.

She also added that the bomb was planted in the room in advance, indicating that the bomb was a high-tech device that used artificial intelligence.

It was detonated remotely by Mossad agents who were on Iranian soil after receiving intelligence that Haniyeh was already in the room.