United Nations Secretary-General Antonio Guterres says civilian objects should not be weaponised after a deadly wave of explosions across Lebanon targeted communication devices used by Hezbollah.

“I think it’s very important that there is an effective control of civilian objects, not to weaponise civilian objects. That should be a rule that … governments should be able to implement,” Guterres said on Wednesday at a briefing at UN headquarters in New York.

Hundreds of wireless paging devices belonging to members of the Iran-backed group exploded simultaneously on Tuesday, hours after Israel said it was broadening the aims of the Gaza war to include its fight against Hamas’s Lebanese ally. The explosions on Tuesday killed 12 people, including two children, and wounded up to 2,800.

Guterres warned that “there is a serious risk of a dramatic escalation in Lebanon, and everything must be done to avoid the escalation”.

“What has happened is particularly serious not only because of the number of victims that it caused but because of the indications that exist that this was triggered, I would say, in advance of a normal way to trigger these things because there was a risk of this being discovered.”

Later on Wednesday, more device blasts across Lebanon killed at least nine people and wounded about 300, according to the country’s Ministry of Public Health.

Lebanon’s state media reported that walkie-talkies used by Hezbollah members blew up in Beirut on Wednesday with reports of similar blasts in southern and eastern Lebanon.

Hezbollah, which has traded near daily cross-border fire with Israeli forces in support of Hamas in the Gaza Strip, said it will retaliate for the pager blasts, which it blamed on Israel.

Israel has not yet commented on the explosions.

Meanwhile, Volker Turk, the UN’s human rights chief, said in a statement on Wednesday that those responsible for the deadly wave of explosions across Lebanon “must be held to account”.

“Simultaneous targeting of thousands of individuals, whether civilians or members of armed groups, without knowledge as to who was in possession of the targeted devices, their location and their surroundings at the time of the attack, violates international human rights law and, to the extent applicable, international humanitarian law,” he said.