More than 1,000 people, including members of the Lebanese militant group Hezbollah have been seriously injured, when pagers they use to communicate exploded, according to security sources.

A Hezbollah official, speaking on condition of anonymity to Reuters, 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.

The Israeli military declined to comment when contacted by Reuters about the detonations.

Iran's semi-official Fars news agency reported that Iran's ambassador to Lebanon, Mojtaba Amani, was slightly injured by the explosion of an electronic pager.

"Amani has a superficial injury and is currently under observation in a hospital," Fars quoted a source as saying.

A witness has told ABC News of seeing one of the pagers exploding on a man riding a motorcycle in the Lebanese capital, Beirut.

Other witnesses have reported ambulances rushing through the southern suburbs of Beirut amid widespread panic.

Residents said explosions took place across the country, including in Lebanon's south, 30 minutes after the initial blasts.

Three security sources told Reuters news agency the pagers that detonated were the latest model brought in by Hezbollah in recent months.

Lebanon's crisis operations centre, which is run by the health ministry, asked all medical workers to head to their respective hospitals to help cope with the massive numbers of wounded coming in for urgent care.

It said health care workers should not use pagers.

Regional news outlets have broadcast CCTV footage which showed what appeared to be a small handheld device spontaneously exploding after being placed next to a grocery store cashier where an individual was paying.

In other footage, an explosion appeared to knock out someone standing at a fruit stand at a market area.

The Lebanese Red Cross said more than 50 ambulances and 300 emergency medical staff were dispatched to assist in the evacuation of victims.