Israel this week vowed to intensify operations in Lebanon and said it was expanding ground operations there, a move that comes ahead of talks on Friday between Lebanese and Israeli military delegations at the Pentagon and a new round of direct negotiations next week aimed at ending the hostilities.

As many Lebanese tried to celebrate the Muslim holiday of Eid al-Adha, the state-run National News Agency (NNA) reported Israeli strikes in the country's south and in the eastern Bekaa valley, with Israel's military saying it was hitting "Hezbollah infrastructure sites" in both regions.

Israel's military issued an evacuation warning for the southern city of Nabatieh for a second consecutive day, and another for swathes of the coastal city of Tyre and surrounding areas.

The NNA and an AFP correspondent in Tyre later said strikes hit the city's outskirts, as Israel's army said it was attacking "Hezbollah command centres" in the area.

Earlier, the correspondent reported residents from threatened areas had converged on parts of the city not covered by the evacuation warning.

Authorities, however, warned that shelters were full and urged people to head to Beirut instead.

- 'Yellow line' -

Iran-backed Hezbollah said its fighters "clashed with the enemy forces at point-blank range" in the town of Zawtar al-Sharqiyah, just beyond the Israeli-declared "yellow line" in south Lebanon where its troops have been operating.

Since early Tuesday, the group had said its fighters had confronted Israeli troops seeking to enter the town, strategically located just six kilometres (four miles) from Nabatieh.

The Israeli troop movement comes after a military official said Tuesday that soldiers had begun operating beyond the "yellow line", which runs around 10 kilometres deep inside Lebanese territory.

Also on Tuesday, Israel stepped up strikes on south and east Lebanon, issuing evacuation warnings for at least 50 towns and villages and killing at least 31 people.

Lebanon's army said that one of its soldiers was among the dead in the east.

At the site of one of the strikes in south Lebanon's Burj al-Shemali, an AFP correspondent saw rescuers removing debris and carrying a white body bag from the rubble, which was littered with items including rugs and cushions.

The NNA, citing the mayor, said 15 people were killed there.

Israeli Prime Minister Benjamin Netanyahu said on Tuesday that the army was "reinforcing the security buffer zone in order to protect the communities of northern Israel".

- West Bekaa -

After Hezbollah drew Lebanon into the Middle East war with rocket fire at Israel in retaliation for strikes that killed Iran's supreme leader, Israel has repeatedly struck Lebanon's eastern Bekaa valley and warned residents to evacuate.

But strikes have intensified in recent days, focusing on the West Bekaa town of Mashghara, where hundreds of displaced people had been sheltering and which has now largely emptied.

Mayor Iskandar Barakeh told AFP that he was worried that "the West Bekaa region is becoming the scene of rear confrontations" between Israel and Hezbollah.

The area links south Lebanon with Hezbollah strongholds in the northern Bekaa and is a key supply route for the group.

Lebanese military expert Hassan Jouni told AFP that the West Bekaa "is a necessary corridor for Hezbollah members if they want to move between the Bekaa and the south" and could become the focus of further Israeli strikes.

He said Israeli operations might soon expand to "target the north Bekaa intensively or even Beirut's southern suburbs", both areas that have been relatively spared since the ceasefire.

A military delegation comprising six Lebanese officers, headed by the army's director of operations Georges Rizkallah, will participate in the talks at the Pentagon on Friday.

A military source told AFP the delegation will "emphasise the need for a ceasefire, and will present the army's plan for a state weapons monopoly and the extension of state authority across the country".