Israel has launched what it has described as "limited, localised and targeted ground raids" in southern Lebanon, marking an escalation in its continuing offensive against Hezbollah.

Lebanese civilians are being warned not to use vehicles to travel south across the Litani river, which is 20 miles north of the Israel-Lebanon border.

According to the Israel Defense Forces (IDF), the operation is aimed at the Iran-backed group's "infrastructure", which it says poses "an immediate threat to Israeli communities in northern Israel".

Hezbollah's deputy leader said the group was prepared for any Israeli operation inside Lebanon.

The group said it targeted Israeli troops with a “rocket barrage” on the Israeli town of Metula and the Avivim area, close to the Lebanon border.

Israel's Defence Minister Yoav Gallant earlier implied the army was ready for a ground operation, telling troops near the Lebanese border Israel was prepared to use forces "from the air, sea and land" to target Hezbollah.

In a statement posted on X at 02:00 local time on Tuesday morning, the IDF confirmed troops had moved across the border following a build-up of tanks and other armour in northern Israel.

The Lebanese army is pulling back troops stationed on its southern border to at least 5km (3 miles) north, according to Reuters news agency, which cited a Lebanese security source.

On Monday, Gallant told Israeli troops at the border that Israel's military would use all "the means at our disposal" to allow displaced people to return home in the north of the country.

In a short video, he said the "elimination" of Hezbollah leader Hassan Nasrallah in Beirut on Friday "is a very important step, but it is not everything".

He added that "everything that needs to be done - will be done" and that "we will use all the forces from the air, sea and land".

The Israeli government has pledged to make it safe for tens of thousands of its citizens to return to their homes after nearly a year of cross-border fighting, which began with Hezbollah firing rockets at the start of the war in Gaza.

The Lebanese armed group - which is proscribed as a terrorist organisation by the US, UK and other countries - is known to have extensive tunnel networks as well as bunkers and other military infrastructure just over the border from Israel.

Hezbollah's deputy chief Sheikh Naim Qassem said the group - which is thought to have tens of thousands of well-trained fighters - was ready for an Israeli ground offensive. He described their attacks on Israel so far as the "minimum", adding that the battle could be long.

Hezbollah - which is backed by Iran - has experienced mass casualties from exploding pagers and walkie-talkies, a wave of assassinations of its military commanders and devastating air strikes which have killed civilians, as well as the use of bunker-busting bombs in Beirut, which killed the group's leader, Hassan Nasrallah, on Friday.

Explosions lit up the night sky on Monday as airstrikes hit Hezbollah’s stronghold of Dahieh, in Beirut's southern suburbs, near the airport.

The attacks came shortly after the Israeli military warned residents to evacuate buildings it said were linked to the group.

In southern Lebanon, there were reports of heavy shelling in the border town of Aita al-Shaab.

And near the city of Sidon, officials say a strike hit a building in a crowded Palestinian refugee camp, the first time it has been attacked in this conflict.

Lebanese officials say more than 1,000 people have been killed in the past two weeks, while up to a million may now be displaced.

On Monday, US President Joe Biden said "we should have a ceasefire now".

"I'm more aware than you might know and I'm comfortable with them stopping," Biden told reporters when asked if he was comfortable with Israeli plans for a cross-border incursion.

UK Foreign Secretary David Lammy spoke to his US counterpart Antony Blinken on Monday, with the US State Department saying they discussed efforts to resolve the conflict. Both men stressed the need for a ceasefire and that the hostages taken by Hezbollah's Palestinian ally Hamas in the 7 October attack on Israel need to be returned home.

The European Union's member states have called for an urgent meeting of the UN Security Council. EU foreign policy chief Josep Borrell said "any further military intervention would dramatically aggravate the situation and it has to be avoided".

Meanwhile, Israel and Hamas have both confirmed the killing of the head of Hamas in Lebanon, Fateh Sherif Abu el-Amin, in Israeli strikes in southern Lebanon.

Israel's military said Sherif was "responsible for co-ordinating Hamas's terror activities in Lebanon with Hezbollah operatives".

Another Israeli strike in the central Beirut neighbourhood of Kola early on Monday killed three members of the Popular Front for the Liberation of Palestine (PFLP), the Palestinian armed group said in a statement.

The statement named those killed as military security chief Mohammad Abdel-Aal, military commander Imad Odeh and fighter Abdel Rahman Abdel-Aal.

Médecins Sans Frontières (MSF) director of communications for Lebanon, Jinane Saad, told the BBC that “we don’t really know where is safe or not” after the strike on the Kola neighbourhood.

“What is safe today might not be safe in an hour or tomorrow,” she said.

The previously sporadic cross-border fighting between Israel and Hezbollah escalated on 8 October 2023 - the day after the unprecedented attack on Israel by Hamas gunmen from the Gaza Strip - when Hezbollah fired at Israeli positions, in solidarity with the Palestinians.