Earlier in the day, the IDF said that dozens of projectiles were fired at northern Israel in the past 24 hours.

It also said that its warplanes conducted “an intelligence-based strike on a command centre of Hezbollah’s intelligence headquarters and an underground weapons workshop in Beirut”.

It said steps had been taken to “reduce the possibility of civilian casualties”.

Israel has been accused by Hezbollah and Lebanese officials of targeting civilians, which it denies.

Earlier on Sunday, the United Nations Interim Force in Lebanon (Unifil) accused the IDF of deliberately demolishing an observation tower and perimeter fence of a UN position in the southern Lebanese town of Marwahin on the border with Israel. It follows similar incidents in recent weeks.

“Yet again, we note that breaching a UN position and damaging UN assets is a flagrant violation of international law and Security Council resolution 1701,” the Unifil said in a statement.

The news came as the Israel Defense Forces (IDF) told residents of another two dozen towns and villages in the south, including the regional capital of Nabatieh, to leave immediately for their own safety.

Unlike the communities ordered to evacuate on Tuesday, they are all located north of the Litani river, which lies about 30km (18 miles) from the border.

Before the invasion, Israel had demanded that Hezbollah’s withdraw to the Litani, in accordance with a UN Security Council resolution that ended their last war in 2006.

Speaking to the BBC from Beirut, the World Food Programme’s country director in Lebanon, Matthew Hollingworth, described the situation there as “horrific”.

“There is black smoke billowing over the southern suburbs and we see it each morning when we come to work and we see it all day long. And there’s a striking number of people who are displaced around the city.”

“There are these cars everywhere that are from people that have fled the fighting in the south of the country and the southern suburbs. There’s traffic everywhere, people sleeping outside.”

Juan Gabriel Wells, Lebanon country director with the International Rescue Committee, said nearly half of displaced people surveyed by his organisation in shelters run by the government were children under the age of 15.

Lebanon’s Annahar newspaper on Wednesday said the Icom walkie-talkies were old handsets.

Reports suggest the walkie-talkies that exploded were purchased by Hezbollah five months ago, according to a security source speaking to Reuters news agency.

Icom produces walkie-talkies and radio devices for marine, aviation and land users, and considers itself a “world leader in the amateur radio market”, according to its website.

Asia is considered a global hub for telecoms and electronics, with countries like Japan, Taiwan and China being home to major tech producers that are often favoured as a benchmark of quality.

BBC Verify investigated BAC Consulting, the company linked to the pagers involved in Tuesday’s explosions, and found that the firm has a single shareholder and is registered to a building in the Hungarian capital Budapest’s 14th district.

As well as BAC, a further 13 companies and one person are registered at the same building. BBC Verify’s search of a financial information database, however, does not reveal that BAC has any connections to other companies or people.

Its CEO Cristiana Bársony-Arcidiacono said she knew nothing about the explosions. “I don’t make the pagers. I am just the intermediate. I think you got it wrong,” she told NBC.