According to Reuters, a Hezbollah official said the detonation of the pagers was the "biggest security breach" the group had been subjected to in nearly a year of war with Israel.

Israel's Mossad planted explosives inside 5,000 Taiwan-made pagers ordered by Hezbollah, months ahead of the mass detonations across Lebanon that killed nine people and injured nearly 3,000 on Tuesday.

Hezbollah had instructed its members to avoid mobile phones and use after the Gaza war began to prevent Israeli breaches.

In a grocery store in Lebanon, Hezbollah members were injured when the pagers they used to communicate exploded. Over 1,000 individuals, including Hezbollah fighters and medics, were injured across Lebanon.

Pagers, widely used in the 20th century, operated by transmitting and receiving radio signals. Their distinctive features, along with privacy and security, made them a preferred communication mode among Hezbollah militants.

Pagers beeped, then blew up.

The attacks left at least 21 dead and thousands injured, but how the blasts occurred remains unclear.

Hundreds of handheld pagers exploded near simultaneously across Lebanon and in parts of Syria on Tuesday, killing at least nine people, including members of the militant group Hezbollah and a girl, and wounding the Iranian ambassador, government and Hezbollah officials said.

Nine people have been killed and 2,800 wounded by the blasts, the Lebanese health ministry says.

Hezbollah has vowed to punish Israel - with Iran's envoy to Beirut among the wounded and a girl killed - in an attack Lebanon's government says is an "Israeli aggression".