Thousands of civilians are racing to flee Beirut after Israeli PM Benjamin Netanyahu ordered the IDF to strike Lebanon's capital city.

Netanyahu and Defence Minister Israel Katz said they had ordered strikes on the Lebanese capital's southern suburbs, a densely populated area where Hezbollah holds sway.

'In light of the repeated violations of the ceasefire in Lebanon by the terrorist organisation Hezbollah and the attacks on our cities and citizens, Prime Minister Benjamin Netanyahu and Defence Minister Israel Katz have instructed the IDF to strike terror targets in the Dahiyeh district of Beirut,' a joint statement said.

Following the announcement, a wave of desperate people were seen fleeing the city, carrying whatever they could. 

Mothers were seen holding their children as they marched along roads, while long, snaking lines of traffic built up on highways leading out of Lebanon's capital. 

Security personnel were seen directing drivers as they fled.   

Lebanon was dragged into the Middle East war on March 2 when Hezbollah fired rockets towards Israel in retaliation for the US-Israeli killing of Iran's supreme leader.

A truce to halt the fighting in Lebanon began on April 17, but has never been observed. Both Israel and Hezbollah accuse each other daily of violating the ceasefire and justify their attacks by the other's alleged breaches.

Iranian foreign ministry spokesman Esmaeil Baqaei said in a weekly press briefing on Monday that 'a ceasefire in Lebanon is an essential condition for any deal aimed at ending the war' with the US.

Lebanese President Joseph Aoun meanwhile said his country was facing 'a vicious and reprehensible Israeli aggression', with the two nations set to hold a fourth round of US-hosted talks on Tuesday.

Hadi, a 24-year-old, said he had hoped for some stability in the area during the truce.

'That feeling did not last long... Our fears intensified this morning after I received a series of messages about orders to bomb the southern suburbs, which caused widespread panic, and we immediately left the area,' he told AFP over the phone.

Beirut's southern suburbs and their surroundings have been struck twice since April 8, when a series of Israeli attacks across Lebanon killed hundreds in minutes.

Monday's Israeli order comes a day after its troops seized the Beaufort castle, which commands sweeping views of south Lebanon, as the military expands its ground operations.

Israeli forces used the castle, also known as Qalaat al-Chakif, as a base during their previous two-decade occupation of southern Lebanon that ended in 2000.

'The capture of Beaufort is a dramatic stage and a dramatic shift in the policy we are leading,' Netanyahu said in a video statement.

French President Emmanuel Macron, whose country requested the UN Security Council meeting, said on Sunday that 'nothing justifies the major escalation under way in south Lebanon', calling for an end to the fighting. 

Lebanese President Aoun condemned the Israeli offensive in a post on X and pledged to 'work to end the suffering of the Lebanese people, and people in the south in particular'.

Earlier on Monday, the Israeli military issued evacuation orders for nine towns and villages in southern Lebanon's Sidon and Jezzine districts, far from the border with Israel, before the army began striking, according to Lebanon's state-run National News Agency.

Hezbollah meanwhile claimed responsibility for a missile fired on Tiberias, around 19 miles into Israeli territory. The Iran-backed group also said it attacked Israeli forces inside Lebanon.

A senior US official told AFP on Sunday that US Secretary of State Marco Rubio had spoken with Aoun and Netanyahu about the ongoing diplomatic negotiations and said Hezbollah must be the first to cease attacks.

Military delegations from Lebanon and Israel held security talks in Washington on Friday and more US-brokered negotiations are planned for Tuesday and Wednesday.

'To advance those talks, the United States proposed a clear sequence: Hezbollah must stop all attacks on Israel. In return, Israel would refrain from escalation in Beirut,' said the official, who spoke on condition of anonymity about the conversations between the three leaders.

Lebanon's health ministry says Israeli attacks have killed more than 3,412 people in the country since early March.

On the Israeli side, 26 Israelis have been killed - 25 soldiers and one civilian contractor - since the start of the war.