Pagers belonging to Hizbollah members exploded across Lebanon on Tuesday, killing at least eight people and injuring more than 2,700 in an apparent sabotage of the low-tech systems the militant group uses to evade Israeli surveillance and assassination attempts.

The blasts took place in several areas of Lebanon including the capital Beirut, the southern city of Tyre and the western area of Hermel. Images circulated on social media of explosions and of people with bloodied pocket areas, ears or faces being taken to hospital.

Iran-backed Hizbollah, the dominant political and military force in Lebanon, blamed Israel for what it described as a “criminal attack”. It said “this treacherous and criminal enemy will certainly receive its just punishment”.

Israel’s military declined to comment, but the incident is likely to heighten tension between two forces that have been locked in intensifying border clashes for almost a year. If Israel was responsible, the attack comes as a humiliating blow to Hizbollah and underscores Israel’s intelligence capability.

Following the blasts, Prime Minister Benjamin Netanyahu on Tuesday evening held consultations with his top security chiefs, including defence minister Yoav Gallant, inside the underground command centre at the military headquarters in Tel Aviv.

Hizbollah said that at about 3.30pm local time “many” pagers belonging to people working in its “different units and institutions exploded”.

Lebanon’s health ministry said eight people including a child had been killed in the blasts and at least 2,750 people were injured, 200 of them seriously.

Iran’s ambassador to Beirut, Mojtaba Amani, was among those injured, an Iranian official told the Financial Times, adding “his overall condition is good”. The Islamic republic’s foreign minister, Abbas Araghchi, “strongly condemned the Zionist regime’s terrorist attack” in a call with his Lebanese counterpart, said Iran’s foreign ministry.

The US said it had no advance knowledge of the attack and had played no operational or intelligence role in the explosions.

“I can tell you that the US was not involved in it,” state department spokesperson Matt Miller said. “The US was not aware of this incident in advance, and at this point, we’re gathering information.”

Miller declined to comment on who was behind the explosions, and said “it’s too early to say” how they would affect Gaza ceasefire negotiations.

“We are always concerned about any type of event that may cause further escalation” in the region, he added.

Lebanon’s health ministry issued an urgent call to its healthcare workers, telling them to go to their workplaces and to stay away from their electronic devices. In the crowded street outside the American University Hospital in central Beirut on Tuesday evening, family members waited tensely, some jostling to be let in.

Ali, an elderly man, said his great-nephew belonged to Hizbollah and had been injured in the leg when his pager exploded. “No one from the family has been able to see him,” he said.

Inside one wing of the hospital was a chaotic queue of would-be blood donors, including Alida, a student who was in class when news of the attacks broke and immediately headed to the hospital to donate.

“We saw the ambulances just keep coming and coming and coming,” she said. “My friends saw cars covered in blood. I saw a line of people on hospital beds with bandages everywhere, blood all over.”

The pager attack comes after Hizbollah turned to low-tech communications as Israel increased assassinations of its senior commanders after the enemies began trading cross-border fire following Hamas’s October 7 attack on Israel.

Over the past 11 months, Israeli strikes have killed about 470 people in Lebanon, mostly Hizbollah fighters, while the militant group’s attacks on Israel have killed more than 40 people.

This year Hassan Nasrallah, Hizbollah’s leader, implored his fighters to jettison their smartphones to avoid surveillance, prompting many to switch to older technologies such as pagers, landlines and human couriers.

That did not prevent the assassination of senior Hizbollah commander Fuad Shukr in an Israeli air strike in July in Beirut’s southern suburbs, the militant group’s stronghold.

Tuesday’s explosions in Lebanon followed what Israel said had been a foiled assassination attempt by Hizbollah on a former senior official in Israel’s security establishment.

Israel’s internal security agency, Shin Bet, said the “planned Hizbollah bombing attack” had “intended to target a former senior official in Israel’s security establishment . . . in the coming days”.

“As part of the operation, the ISA uncovered a Claymore explosive device . . . intended to target a high-profile individual,” it added. “The device was equipped with a remote activation mechanism, with a camera and cellular technology, enabling it to be activated by Hizbollah from Lebanon.”

Earlier on Tuesday, Netanyahu’s security cabinet expanded the objectives of Israel’s almost year-long campaign against Hamas in Gaza to include securing the northern front against Hizbollah.

It voted to add “returning the residents of the North securely to their homes”, in reference to more than 60,000 Israelis who have been displaced by the clashes on the Israeli-Lebanese border. The fighting has also forced about 100,000 Lebanese from their homes in the border region.

The security cabinet’s decision was viewed by analysts as a statement of intent, marking a shift in priorities for the Israel Defense Forces and raising fears that the clashes between Hizbollah and Israel could spiral into a full-scale war.

Additional reporting by Neri Zilber in Tel Aviv, Andrew England in London and Steff Chávez in Washington