Israel’s military has warned civilians to avoid Hezbollah positions as it pounds southern Lebanon, while it was reported that phone warnings have been received across the country.

The Israeli army reported on Monday that its warplanes had launched more than 300 strikes in Lebanon. In an earlier message, the military warned of further action against the Iran-backed armed group, which launched a barrage of missiles into northern Israel the previous day.

The intensification of the fighting across the shared border, which has seen low-level skirmishes since Israel launched its war on Gaza in October, follows last week’s explosions of pagers and walkie-talkies which killed dozens in Lebanon. The increased hostilities further raise fears of an all-out war between Israel and Hezbollah, or even a wider regional conflagration.

In the early hours of Monday, Israeli military spokesperson Daniel Hagari said the army had conducted “extensive strikes” against Hezbollah posts after identifying attempts to fire missiles. Israel’s government recently declared that it was shifting more focus to the fighting with Hezbollah in a bid to allow the 60,000 or so Israelis evacuated from the border areas to return.

Israeli Defence Minister Yoav Gallant called on the public to remain calm as the military broadened its assault.

“We are deepening our attacks in Lebanon, the actions will continue until we achieve our goal to return the northern residents safely to their homes,” Gallant said in a video published by his office on Monday. “These are days in which the Israeli public will have to show composure.”

‘Psychological war’

Hagari warned residents in southern Lebanon to leave areas in which the armed group has positions. Civilians in the area received calls with the same message.

“We advise civilians from Lebanese villages located in and next to buildings and areas used by Hezbollah for military purposes, such as those used to store weapons, to immediately move out of harm’s way for their own safety,” Hagari told journalists.

Asked by a reporter whether the army was planning a ground invasion into the neighbouring country, Hagari said “we will do everything necessary to return the residents of the north to their homes safely.”

Lebanese media reported that people across the country, including the capital Beirut in central Lebanon, have been receiving Israeli phone warnings telling them to evacuate.

Lebanon’s National News Agency (NNA) reported that “citizens in Beirut and a number of areas are receiving landline telephone warning messages whose source is the Israeli enemy, asking them to quickly evacuate.”

Information Minister Ziad Makary’s office in Beirut said it received a landline call featuring a “recorded message” that told them to evacuate the building in order to avoid an air strike.

NNA labelled the phone warnings “part of the psychological war that the enemy has adopted”.

Reporting from Beirut, an Al Jazeera correspondent said that people are “anxious about not only what is happening in the south, but about how close they are to actually being in a full-out war between Hezbollah and Israel”.

Israel and Lebanon are technically at war, and Lebanon forbids communications with Israel.

An official at state telecommunications provider Ogero told the AFP news agency that while the landline network system in Lebanon blocks all communication, Israel “circumvents the communications systems by using the international phone code of a friendly country”.

‘Battle of reckoning’

An Al Jazeera reporter stationed near the village of Marjayoun in southern Lebanon counted at least 10 air strikes at about 04:30 GMT, adding that Israel had hit several towns and villages in the south, as well as in the Bekaa Valley in eastern Lebanon.

Footage showed columns of smoke. Hezbollah’s al-Manar TV reported that Israeli warplanes also struck the Hermel area in northern Lebanon.

White House spokesperson John Kirby said the US still believes there is room for a “diplomatic solution” while warning Israel that there are “better ways” to allow its residents to return to their houses in the north.

Hezbollah deputy chief Naim Qassem told mourners at the funeral of one of the group’s commanders killed last week in Beirut: “We have entered a new phase, the title of which is the open-ended battle of reckoning.”

On Saturday, Hezbollah launched dozens of rockets at Israel’s Ramat David Airbase, east of Haifa in its farthest-reaching attack inside Israel.

Monday’s salvo was among the heaviest cross-border fire exchanges between Israel and Hezbollah since the start of the war in Gaza.

The two parties have been exchanging nearly daily fire since October 8, with the Iran-backed group saying it would stop only once a ceasefire was achieved in the Palestinian enclave.

But while those exchanges were largely confined to border areas and were aimed at primarily military targets, they have escalated dramatically this week.

Israel’s shift of focus was initiated in a wave of unprecedented attacks. On Tuesday and Wednesday, thousands of pagers and other devices exploded in Beirut targeting Hezbollah’s rank and file members, as well as civilians, sending shockwaves across the country.

At least 37 people were killed and more than 3,000 were wounded in the blasts. These were widely blamed on Israel which has neither confirmed nor denied responsibility.

On Friday, an Israeli strike killed a senior commander of Hezbollah’s Radwan unit, and the second-in-command of the group’s armed force Ibrahim Aqil.

The strike in the Beirut suburb of Dahiyeh killed at least 45 people, including 10 civilians.