Israel declared a new phase of war after it was accused of a second wave of remote-controlled explosions in Lebanon.

Hundreds of walkie-talkie radios and other electronic devices began exploding in Lebanon on Wednesday afternoon during the funeral for Hezbollah fighters killed in a near-identical attack on pagers the previous day.

Lebanon’s health ministry said 14 people had been confirmed killed and a further 450 wounded. The Lebanon-based group fired 20 rockets into Israel following the blasts, Israeli officials said. All were intercepted.

Shortly after the explosions, Israel’s defence minister said that the country was shifting its military focus to the north towards the Lebanese border for a “new phase” of the 11-month war that has raged since the Hamas attacks on October 7 last year.

Yoav Gallant, Israel’s minister of defence, said: “The centre of gravity is shifting to the north, by diverting resources and forces [there].

“We are at the onset of a new phase in the war. It requires courage, determination and perseverance from us.”

The remarks will raise fears of a full-scale Israeli assault on Hezbollah in Lebanon. Experts cautioned, however, that the US would resist any such invasion, which would also have a high political cost in Israel.

Israel this week said returning about 60,000 evacuees to their homes in northern Israel was an official war aim.

Benjamin Netanyahu, the Israeli prime minister, did not directly address the attacks or the prospect of war in televised remarks on Wednesday.

“I already said that we would return the residents of the north securely to their homes and that is exactly what we will do,” he said.

Hassan Nasrallah, Hezbollah’s leader, is expected to deliver a televised address in response to the attacks on Thursday.

The head of Hezbollah’s executive council said on Wednesday that the injured fighters would soon go back to the “battlefields.”

“These attacks will certainly be uniquely punished,” Seyed Hashem Safiuddin warned. “Revenge is inevitable.”

Hezbollah began firing rockets into northern Israel after Israel attacked Gaza in response to the Hamas massacre of October 7. Israel has responded with airstrikes in a tit-for-tat conflict that has so far not escalated to full-scale war.

Wednesday’s remote-controlled explosions saw radios, security doors and home solar power systems simultaneously detonated across Lebanon in the second such attack in as many days.

A security source told Lebanese news outlet L’Orient Today that devices were detonated inside cars, residential apartments and shops.

Footage from Beirut showed cars and motorcycles burning in the street. One explosion went off in the crowd at the funeral of a Hezbollah member killed in the previous attack on Tuesday.

Lebanon’s state news agency reported three people were confirmed killed in the Bekaa Valley in the east of the country. The country’s health ministry later revised that figure down to one.

It came 24 hours after thousands of hand-held pagers used by members of Hezbollah simultaneously detonated on Tuesday afternoon, plunging Lebanon into chaos.

That attack killed at least 12 people, including two children, and injured nearly 3000.

Israel has refused to comment on allegations that it is behind the attacks, in line with its long-standing policy of neither confirming nor denying covert operations.

Reports suggest the attacks in Beirut were the product of a months-long operation by Mossad, the Israeli overseas intelligence agency.

The “supply chain attack” appears to have seen a small explosive charge hidden in thousands of pagers and other electronic devices ordered by the militant group.

The Telegraph understands a number of Hezbollah operatives raised suspicions about the devices shortly before the attack, which may have prompted the Israelis to launch the operation prematurely.

“It was a use it or lose it moment,” one US official told the Axios website.

Some reports suggested the explosives were originally intended to be used only in the event of an all-out war, and that Israel might feel compelled to launch a ground invasion to cripple Hezbollah before the shock of the attack dissipates.

The Telegraph could not immediately confirm those claims.

The Israeli Defense Forces on Tuesday deployed its elite 98th division from Gaza to its northern border with Lebanon.

Troops in Israel’s northern command conducted two exercises this week focusing on “readiness for terrain in the north, including simulating operations in enemy territory, and evacuating wounded from the field under fire”.

Maj Gen Ori Gordin, the head of northern command, said on Wednesday that his troops were at “peak readiness” and were “determined to change the security reality as soon as possible”.

Hezbollah is generally considered a more formidable opponent for Israel than Hamas.

The Iranian-backed Shia group is believed to have amassed between 100,000 and 150,000 rockets that it could fire into Israel in the event of an all-out war.

Israel’s ground invasion of Lebanon to root out Hezbollah, in 2006, lasted 32 days and ended inconclusively.

Danny Yatom, a former Mossad chief, refused to discuss attribution for Wednesday’s attacks but told The Telegraph that whoever was behind it would have had to “put their hands” on the devices before arriving in Lebanon.

He added that the number of wounded Hezbollah members was more significant than the damage done to its communications network.

“That should worry Hezbollah and its leader, Hassan Nasrallah. The main problem for Hezbollah is not a different communication system but how many terrorists are injured.

“If they (Hezbollah members) are severely injured they won’t be able to operate as terrorists,” Mr Yatom said.

The move has alarmed Israel’s closest allies, with both the United States and Britain urging restraint.

Antony Blinken, the US secretary of state, on Tuesday expressed frustration that the explosions in Lebanon could derail efforts to conclude a ceasefire in Gaza.

“Time and again” when the US and other mediators believed they were making progress on a cease-fire deal, “we’ve seen an event that ... threatens to slow it, stop it, derail it,” he said when asked about the explosions in Lebanon.

The British Government said de-escalation was a priority and urged British citizens to leave Lebanon.

A Foreign Office spokesman said: “We continue to monitor the situation in Lebanon closely and are concerned by the rising tensions and civilian casualties in Lebanon. The UK is working with diplomatic and humanitarian partners in the region.

“We urge calm heads at this critical time and a focus on a negotiated settlement.”

The booby-trap attacks have also drawn criticism for putting civilians at risk. At least two children were killed in the first attack on Tuesday afternoon.

The family of Fatima Abdallah, 10, said she had been killed when her father’s pager exploded.

Josep Borrell, the European Union’s top diplomat, suggested the attack was legally questionable, given the collateral damage caused, as well as warning it violated Lebanon’s national sovereignty and risked regional escalation in the Middle East.

“Even if the attacks seem to have been targeted, they had heavy, indiscriminate collateral damages among civilians: several children are among the victims,” he said after talks with Abdallah Bou Habib, Lebanon’s foreign minister.

Jeanine Hennis-Plasschaert, the United Nations special co-ordinator for Lebanon, also raised concerns about the legality of the attack, adding: “Even one civilian casualty is one too many.”

Petra De Sutter, Belgium’s deputy prime minister, went as far as to describe the sabotage plot as a “terror attack”.

CCTV footage showed at least one of the rigged pagers exploding in a crowded greengrocer’s store.

International humanitarian law largely prohibits the use of “booby traps”.

The UN’s convention on certain conventional weapons rules that “it is prohibited in all circumstances to use … any booby-trap in the form of an apparently harmless portable object which is specifically designed and constructed to contain explosive material”.

The UK’s rules of engagement also puts a ban on items designed to contain explosives resembling harmless items.

The US law of war manual gives examples of rigged watches, cameras and toys to be avoided to “prevent the production of large quantities of dangerous objects that can be scattered around and are likely to be attractive to civilians, especially children”.

But Washington’s rules do not ban booby traps, only when they are “intentionally designed to look harmless”.