The United Nations Interim Force in Lebanon (UNIFIL) said two peacekeepers were killed and two others wounded, one of them seriously, "when an explosion of unknown origin destroyed their vehicle" in south Lebanon near the border.

Also in the south, Lebanon's army said an Israeli strike killed one of its soldiers, while a security source told AFP that three Hezbollah members were killed in an Israeli strike on Beirut's southern suburbs.

Lebanon was pulled into the Middle East conflict when the Tehran-backed armed group Hezbollah fired rockets at Israel on March 2 in revenge for the killing of Iran's supreme leader, the opening salvo in the US-Israeli war against the Islamic republic.

Israel has responded with large-scale air strikes across Lebanon and a ground offensive in the south. Lebanese authorities say more than 1,200 people have been killed since the hostilities began.

UNIFIL said it had launched an investigation into the deadly incident, which came a day after an Indonesian peacekeeper was killed and three other blue helmets wounded when a projectile, also of unknown provenance, exploded near a UNIFIL position.

Jean-Pierre Lacroix, UN under-secretary-general for peace operations, strongly condemned "these unacceptable incidents", adding that "all acts that endanger the peacekeepers must stop".

Lebanese President Joseph Aoun condemned "the targeting of peacekeeping forces" in a phone call with UNIFIL's commander.

Permanent member France said it was seeking a UN Security Council meeting on the matter.

- 'Direct' attack -

Aoun "continues to conduct multiple international contacts to push matters towards achieving negotiations with Israel", the Lebanese presidency said in a statement.

In southern Lebanon, where state media reported a series of Israeli air strikes, the Lebanese army said one of its soldiers was killed and five others wounded in "a direct Israeli attack on an army checkpoint" in the Tyre region.

A military source told AFP that the strike was the first direct targeting of a Lebanese army checkpoint since the latest war began.

The army had previously announced the deaths of eight off-duty soldiers in southern and eastern Lebanon.

Two strikes hit Beirut's southern suburbs, one of them targeting an apartment in a residential building in the Bir Hassan district, according to an AFP photographer, who said Hezbollah gunmen imposed a security cordon at the site after the attack.

A security source told AFP that three Hezbollah members were killed in the strike and three others wounded.

The health ministry reported one person killed and 17 wounded in the strike.

An eyewitness who declined to be identified said victims were evacuated following the strike, which came after an Israeli army evacuation warning for parts of Beirut's southern suburbs, where most residents have fled.

The building targeted is located in a residential neighbourhood packed with shops and commercial establishments, several of which were damaged, according to the photographer.

- Evacuation order -

The Israeli military said in a statement that a strike in Beirut killed the deputy commander of a unit "responsible for coordinating between the Hezbollah terrorist organisation and Palestinian terrorist organizations operating in Lebanon, Gaza, Syria" and the Israeli-occupied West Bank.

The strike also killed the unit's "operations officer" and another operative, it's said.

Other strikes in Beirut and south Lebanon targeted Hezbollah "command centres", the military said.

Later on Monday, it issued an evacuation warning for parts of Lebanon's West Bekaa area.

Hezbollah, meanwhile, claimed a series of attacks against Israeli targets in south Lebanon and across the border, including on an intelligence base on the outskirts of Tel Aviv.

It said its fighters were engaged in "fierce clashes" with Israeli forces in the town of Ainata near the border.

Also on Monday, the Israeli military said one of its soldiers was killed fighting in south Lebanon, and another seriously wounded, bringing the number of Israeli soldiers killed in Lebanon to six this month.