Hezbollah promised to retaliate against Israel after accusing it of detonating pagers across Lebanon on Tuesday, killing at least eight people and wounding nearly 3,000 others who included fighters and Iran's envoy to Beirut.

Lebanese Information Minister Ziad Makary condemned the late afternoon detonation of the pagers - handheld devices that Hezbollah and others in Lebanon use to send messages - as an "Israeli aggression". Hezbollah said Israel would receive "its fair punishment" for the blasts.

The Israeli military, which has been engaged in cross-border fighting with Iran-backed Hezbollah since the start of the Gaza war in October, declined to respond to questions about the detonations.

Lebanese Health Minister Firass Abiad said on Tuesday that eight people were killed and 2,750 wounded in the pager explosions, 200 of them critically.

Hezbollah in an earlier statement confirmed the deaths included at least two of its fighters and a little girl.

The pagers exploded in southern Lebanon, the southern suburbs of Beirut known as Dahiyeh and the eastern Bekaa Valley - all Hezbollah strongholds.

In one instance, closed-circuit surveillance video carried by regional broadcasters showed a person paying at a grocery store as what appeared to be a small handheld device placed next to the cashier exploded.

A Hezbollah official, speaking on condition of anonymity, said the detonation of the pagers was the "biggest security breach" for the group in nearly a year of conflict with Israel.

The Palestinian militant group Hamas, which is waging war with Israel in Gaza, said the pager blasts were an "escalation" that will only lead Israel to "failure and defeat".

The U.S. State Department said it was too early to say how the pager attacks in Lebanon might impact efforts to secure a ceasefire in Gaza.

It urged Iran -- which with its allies Hezbollah, Yemen's Houthis and armed groups in Iraq has formed an "Axis of Resistance" against Israeli and U.S. influence -- not to take advantage of any incident to raise instability.

Without commenting directly on the explosions in Lebanon, an Israeli military spokesman said the chief of staff, Major General Herzi Halevi, met with senior officers on Tuesday evening to assess the situation. No policy change was announced but "vigilance must continue to be maintained", he said.

Hezbollah fighters have been using pagers as a low-tech means of communication in the belief they could evade Israeli location tracking, two sources familiar with the group's operations told Reuters earlier this year. A pager is a wireless telecommunications device that receives and displays messages.