Apostolic Nuncio Paolo Borgia, who was travelling in the convoy, was being escorted by French peacekeepers from the United Nations Interim Force in Lebanon (UNIFIL), and was en route to the village of Debl near the Israeli border, the source told AFP on condition of anonymity.

His convoy came under fire as it approached border villages, with vehicles sustaining damage but no casualties reported, according to the source, who is on the ground in south Lebanon.

A number of Christian-majority villages near the border, including Debl, have been caught up in the fighting between Israel and Hezbollah.

The militant group drew Lebanon into the wider Middle East war on March 2 with rocket fire towards Israel in support of its backer Iran.

Israel has responded with heavy strikes and a ground invasion in the country's south.

The source said that after several attempts to proceed, the convoy finally turned back after an unidentified projectile exploded nearby.

The state-run National News Agency reported that the convoy turned around after waiting more than two hours near the border town of Bint Jbeil "due to exchanges of fire and the intensification of fighting".

Residents of Christian villages have been refusing to leave despite the Israeli army's advance and sweeping evacuation orders for swathes of south Lebanon.

The villagers say it is not their war and that they feel abandoned after the Lebanese army withdrew from several border locations.

In Rmeish, another frontier village, the local municipality has launched a campaign on social media seeking donations of basic necessities including medication and baby formula.

Borgia had organised previous aid convoys to Christian border villages since the war erupted.

A visit planned for Sunday was cancelled for security reasons.