(AFP) - Israel pounded southern Lebanon Saturday, raising fears of all-out war a day after an Israeli strike on Beirut left senior Hezbollah commanders among the 37 people Lebanese officials said were killed.

With heavy equipment still working at the site of the southern Beirut strike beneath high-rise buildings, Lebanon's health ministry reported six additional dead, up from 31 earlier Saturday.

AFPTV footage showed mourners gathering in the Lebanese capital on Saturday for the funerals of three slain Hezbollah members.

Lebanese Prime Minister Najib Mikati decried "horrific massacres" and said he had cancelled his trip to the annual United Nations General Assembly in New York, "in light of the developments linked to the Israeli aggression".

Germany's foreign ministry said there was "an urgent need" to defuse tensions, as the Israel-Hamas war in the Gaza Strip threatens to engulf Lebanon too.

The UN has also voiced concern about "heightened escalation" and called for "maximum restraint" from all sides.

Israeli aircraft "struck thousands" of rocket launchers ready to fire from southern Lebanon, as well as "approximately 180" other, unspecified targets, a military statement said.

AFP correspondents reported intense Israeli strikes over a wide area of southern Lebanon including parts of the Nabatiyeh district and Jezzine further north.

- Basement bombed -

Iran-backed Hezbollah said it targeted at least seven military positions in northern Israel and the annexed Golan Heights with rockets.

Israel's military said the militants had fired "about 90" rockets by late afternoon Saturday.

Lebanon's Health Minister Firass Abiad said three children and seven women were killed in Friday's strike on an underground meeting room, which AFP journalists said left a huge crater in a densely populated neighbourhood of the capital's southern suburbs, a Hezbollah stronghold.

Israel said the strike killed the head of Hezbollah's elite Radwan Force, Ibrahim Aqil, and several other commanders.

Israel's military said it conducted a "targeted strike" against Aqil, which a source close to Hezbollah said killed 16 Radwan Force members.

"The command of the Radwan Force was meeting in the basement of the building," the source said.

The Radwan Force has spearheaded Hezbollah's ground operations, and Israel has repeatedly demanded through international mediators that its fighters be pushed back from the border.

Confirming the death of Aqil, Hezbollah hailed him as "one of its great leaders".

Washington had offered a $7 million reward for information on Aqil, calling him a "principal member" of an organisation that claimed the 1983 Beirut US embassy bombing which killed 63.

- Exploding pagers -

Hezbollah said a second senior commander, Ahmed Mahmud Wahbi, was also killed on Friday. It said he headed the group's operations against Israel from the onset of the Gaza war in October until the start of this year.

It was the second Israeli strike on Hezbollah's military leadership since the Gaza war began. In July, an Israeli strike on Beirut killed Fuad Shukr, a top operations chief.

Friday's strike also followed sabotage attacks on pagers and two-way radios used by Hezbollah on Tuesday and Wednesday, which killed 39 people. Hezbollah blamed Israel, which has not commented.

Hezbollah chief Hassan Nasrallah vowed that Israel would face retribution for those blasts.

For nearly a year, Hezbollah fighters in Lebanon have traded cross-border fire with Israeli forces in stated support of Palestinian ally Hamas, whose October 7 attack on Israel triggered the war in Gaza.

After Friday's strike, Israeli Defence Minister Yoav Gallant said Israel's "enemies" would find no refuge.

Iran accused Israel of seeking to "broaden the geography of the war", and Hamas called the Beirut strike an "escalation".

Military spokesman Rear Admiral Daniel Hagari said Israel was "not aiming for a broad escalation in the region".

The months of near-daily exchanges have killed hundreds in Lebanon, mostly fighters, and dozens in Israel and the annexed Golan Heights, forcing tens of thousands on both sides to flee their homes.

Israeli Prime Minister Benjamin Netanyahu delayed by a day his departure for the United States, where he is due to address the UN General Assembly.

On Friday the UN's High Commissioner for Human Rights, Volker Turk, told the Security Council the attack on Hezbollah communications devices violated international law and could constitute a war crime.

International mediators, including the United States, have been scrambling to stop the Gaza war from becoming a regional conflict.

Critics of Netanyahu in Israel, demanding a deal to free hostages held by Hamas, have accused the prime minister of dragging out the war.

- Gaza school strike -

In Gaza on Saturday, the civil defence agency said an Israeli strike on Al-Zeitun School C, which had been turned into a displaced shelter, killed 21 people including 13 children and six women, one of them pregnant.

Israel's military said the strike targeted Hamas militants who were "embedded inside" an adjacent school, and that it had taken steps "to mitigate the risk of harming civilians".

An AFP reporter confirmed Al-Zeitun School C was hit.

In late August the United Nations said Israel had struck at least 23 school shelters since July 4.

Israel has repeatedly accused Hamas of operating from such facilities in highly urbanised Gaza, a charge the militants deny.

In a separate incident, Gaza's health ministry said an Israeli air strike hit a southern Gaza warehouse killing four people, mostly health ministry personnel.

The October 7 attack that triggered the war resulted in the deaths of 1,205 people, mostly civilians, on the Israeli side, according to an AFP tally based on Israeli official figures that include hostages killed in captivity.

Of 251 hostages seized by militants, 97 are still held in Gaza, including 33 the Israeli military says are dead.

Israel's retaliatory military offensive has killed at least 41,391 people in Gaza, most of them civilians, according to figures provided by the Hamas-run territory's health ministry. The UN has acknowledged the figures as reliable.

© Agence France-Presse