The assassination of Hamas political chief Ismail Haniyeh was carried out in Tehran this week using an explosive device that was hidden months ago inside the guesthouse where he was staying, a report says. 

The bomb ended up being remotely detonated around 2 a.m. local time Wednesday, killing Haniyeh and a bodyguard at the compound protected by the Islamic Revolutionary Guards Corps in the northern part of Iran’s capital, Middle Eastern officials told The New York Times. 

Haniyeh was in Tehran for Iranian President Masoud Pezeshkian's swearing-in on Tuesday. The State Department did not immediately respond to a request for comment from Fox News Digital about the report. 

The officials, speaking on condition of anonymity, told The New York Times that the explosive device was placed in the room where Haniyeh was staying around two months ago and was set off on Wednesday once it was confirmed that he was there. 

HAMAS LEADER ISMAIL HANIYEH IS ASSASSINATED 

Ismail Haniyeh, the Doha, Qatar-based political bureau chief of Hamas, speaks to the press after a meeting with the Iranian Foreign Minister Hossein Amir-Abdollahian in Tehran on March 26, 2024.  (AFP via Getty Images)

They said Haniyeh had stayed at the guesthouse several times before while visiting Tehran, adding that Israeli intelligence officials later briefed their counterparts in the U.S. and other Western governments about the operation in its immediate aftermath. 

Israel has not come out publicly to claim responsibility for the killing, but Iran and Hamas are blaming the Jewish State for being behind it, according to The Associated Press. 

Three Iranian officials separately told The New York Times that the security breach that allowed the explosive device to find its way into the compound where Haniyeh was residing – which is used by the Guards for secret meetings and housing prominent guests – is a massive embarrassment to the military agency. 

IRAN’S AYATOLLAH ALI KHAMENEI ORDERS ‘DIRECT’ ATTACK ON ISRAEL: REPORT 

Iranian Supreme Leader Ayatollah Ali Khamenei, center, leads a prayer over the coffins of Hamas leader Ismail Haniyeh and his bodyguard who were killed in an assassination blamed on Israel on Wednesday. (Office of the Iranian Supreme Leader via AP)

It’s unclear how the bomb allegedly was stashed inside the property. 

U.S. Secretary of State Antony Blinken – when asked Wednesday about the matter – said he has "seen the reports." 

"And what I can tell you is this. First, this is something we were not aware of or involved in," Blinken said. "It’s very hard to speculate, and I’ve learned over many years never to speculate on the impact one event may have on something else. So I can’t tell you what this means.  

Iranians follow a truck, center, carrying the coffins of Hamas leader Ismail Haniyeh and his bodyguard, during their funeral ceremony in Tehran, Iran, on Thursday, Aug. 1. (AP/Vahid Salemi)

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"I can tell you that the imperative of getting a ceasefire," in Gaza, "the importance that that has for everyone, remains," he also said. 

Fox News’ Landon Mion contributed to this report.