US Secretary of State Antony Blinken has said the United States “was not aware of or involved in” the killing of Hamas political leader Ismail Haniyeh, which has escalated already heightened tensions across the Middle East.

In an interview with Channel News Asia on Wednesday, Blinken said he did not want to speculate as to what effect Haniyeh’s killing in the Iranian capital would have.

“This is something we were not aware of or involved in,” the top US diplomat 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.”

Haniyeh’s killing in the early hours of Wednesday in Tehran, where he was attending the swearing-in ceremony of Iran’s new President Masoud Pezeshkian, has been condemned by leaders across the region and raised concerns about further escalation.

Hamas, the Palestinian political faction that governs the Gaza Strip, has blamed Israel for the attack that killed its political leader, saying Haniyeh was killed in a “treacherous Zionist raid”.

Iran’s Leader, Ayatollah Ali Khamenei, also promised “harsh punishment” for Israel in retaliation for the assassination, saying it is Tehran’s duty to avenge Haniyeh.

Reporting from the Lebanese capital Beirut on Wednesday, Al Jazeera’s Zeina Khodr said recent responses to Haniyeh’s killing suggest there could be a “coordinated response” from Iran and its regional allies.

“In Iran, they are hoisting the red flag – the flag of revenge. So there is a lot of anger,” she said.

Israel also carried out a bombing in Beirut just hours before Haniyeh was killed, saying it targeted Fuad Shukr, a commander of the Lebanese group Hezbollah. At least three people, including two children, were killed and 74 others wounded.

Haniyeh, 62, had been involved in negotiations to try to secure a ceasefire in Gaza, where Israeli attacks have killed at least 39,445 Palestinians since early October.

The prime minister of Qatar, which has acted as a mediator in Gaza ceasefire negotiations between Israel and Hamas, questioned the chances of the talks succeeding following the assassination.

“How can mediation succeed when one party assassinates the negotiator on the other side?” Sheikh Mohammed bin Abdulrahman bin Jassim Al Thani posted on social media.

In Wednesday’s interview with Channel News Asia, the US’s Blinken said, “The imperative of getting a ceasefire, the importance that has for everyone, remains”.

“We will continue to labor that for as long as it takes to get there,” Blinken said.

“It’s vitally important to help end the suffering of Palestinians in Gaza. It’s vitally important in getting the hostages [held in Gaza] home, including a number of Americans. It’s vitally important to hopefully put things on a better path for more enduring peace, for more enduring security.”

The US government has been widely criticised for providing unwavering support to Israel, including military aid and equipment, during the Gaza war.

Human rights advocates have urged US President Joe Biden’s administration to end weapons shipments to Israel as the conflict drags on.