Clashes broke out late Sunday at the Syrian-Lebanese border, with the new authorities in Damascus accusing the Lebanese armed group Hezbollah of abducting three soldiers into Lebanon and killing them.

A Lebanese security source told AFP that Syrian forces fired shells into Lebanon after the three security personnel were killed in the Lebanese village of Qasr by local gunmen involved in smuggling.

Lebanon's state-run National News Agency (NNA) said the border clashes resumed on Monday following fresh Syrian shelling.

"What is happening on the eastern and northeastern borders cannot continue," Aoun said in a post on X. "I have directed the Lebanese army to respond to the source of the fire."

The army announced that its units had "responded to the sources of fire with appropriate weapons" after the renewed shelling from Syrian territory, NNA reported.

It added that its units "are working to strengthen their defensive positions to stop attacks on Lebanese territory".

The army said earlier that it had undertaken "exceptional security measures and intensive communications" since Sunday night that had led to the return of the three Syrian soldiers' bodies to authorities there.

Lebanese Information Minister Paul Morcos said one child had been killed and six other people wounded by the Syrian shelling, adding that many civilians had also been displaced in the border area.

A source in Syria's defence ministry later told state news agency SANA that forces had launched a security sweep of the border areas.

"Our aim with our actions on the border is to expel Hezbollah militias from the Syrian villages and areas they use as temporary bases for smuggling and drug trafficking operations," the source said.

Earlier Monday, Syrian authorities in Homs province reported that a photographer and a journalist were wounded along the border, according to SANA.

They accused Hezbollah of "targeting them with a guided missile".

Hezbollah was a key backer of Syria's former president Bashar al-Assad before he was toppled in a lightning offensive by Islamist-led rebels in December.

Syria's new authorities announced last month the launch of a security campaign in the border province of Homs aimed at shutting down routes used for arms and goods smuggling.

Under Assad, Syria had been a key link in Iran's anti-Israel "axis of resistance", serving as a conduit for weaponry flowing to fellow Tehran ally Hezbollah.

The new authorities in Damascus have accused Hezbollah of launching attacks, saying it was sponsoring cross-border smuggling gangs.

Speaking at a donor conference for Syria in Brussels, Foreign Minister Asaad al-Shaibani said Damascus would "not tolerate any attempts to undermine Syrian sovereignty".

He accused "outlawed parties", including "some militias stationed on our borders with neighbouring countries", of posing a persistent threat to Syria's security and stability, without naming a particular group.