Hundreds of pagers used by Hezbollah members exploded across Lebanon on Tuesday, killing at least nine people and wounding some 2,800 in blasts which the Iran-backed militant group blamed on Israel.

There was no immediate comment from the Israeli military on the wave of explosions, which came just hours after Israel announced it was broadening the aims of the war sparked by Hamas's October 7 attacks to include its fight against Hezbollah along its border with Lebanon.

The sons of Hezbollah lawmakers Ali Ammar and Hassan Fadlallah were among the dead, a source close to the group told AFP, requesting anonymity to discuss sensitive matters.

The blasts "killed nine people, including a girl", Lebanese Health Minister Firass Abiad said in a casualty update.

He added that some "2,800 people were injured, about 200 of them critically" with injuries mostly reported to the face, hands and stomach.

The 10-year-old daughter of a Hezbollah member was killed in east Lebanon's Bekaa Valley when his pager exploded, the family and a source close to the group said.

Tehran's ambassador to Beirut was also wounded in a pager explosion but his injuries were not serious, Iranian state media reported.

In neighbouring Syria, 14 people were wounded "after pagers used by Hezbollah exploded", said a Britain-based war monitor, the Syrian Observatory for Human Rights.

Hezbollah blamed Israel for the blasts and warned it would be punished.

"We hold the Israeli enemy fully responsible for this criminal aggression," the group said in a statement, adding that Israel "will certainly receive its just punishment for this sinful aggression".

The United States, Israel's top arms provider and close ally, was "not involved" and "not aware of this incident in advance", said State Department spokesman Matthew Miller.

The afternoon blasts hit Hezbollah strongholds across Lebanon and dealt a heavy blow to the militant group, which already had concerns about the security of its communications after losing several key commanders to targeted air strikes in recent months.

Hezbollah had instructed its members to avoid mobile phones after the Gaza war began and to rely instead on the group's own telecommunications system to prevent Israeli breaches.

"Hundreds of Hezbollah members were injured by the simultaneous explosion of their pagers" in the group's strongholds in Beirut's southern suburbs, in south Lebanon and in the eastern Bekaa Valley, a Hezbollah source said, requesting anonymity.

AFP journalists saw dozens of wounded being taken to hospital in Beirut and in the south, where dozens of ambulances rushed between the cities of Tyre and Sidon in both directions.

Education Minister Abbas Halabi announced the closure of schools and universities on Wednesday "in condemnation of the criminal act committed by the Israeli enemy".

- Israel expands war aims -

Earlier Tuesday, Israel announced it was broadening the aims of the war sparked by the Hamas attacks to include its fight against Hezbollah along its border with Lebanon.

To date, Israel's objectives have been to crush Hamas and bring home the hostages seized by Palestinian militants during the October 7 attacks that sparked the war.

"The political-security cabinet updated the goals of the war this evening, so that they include the following section: the safe return of the residents of the north to their homes," Israeli Prime Minister Benjamin Netanyahu's office said in a statement. (AFP)