Israeli "aircraft conducted a precise intelligence based strike on an underground tunnel crossing from Syrian territory into Lebanese territory that was used by Hezbollah to smuggle weapons," the military said a day after it struck a weapons depot used by Palestinian militant group Hamas in southern Syria.

In its strikes on Sunday, the military said it also struck "several other Hezbollah sites" in Lebanon.

Lebanon's official National News Agency on Sunday reported "hostile Israeli warplanes" launching several raids at the Lebanon-Syria border, including one which targeted a crossing.

A fragile Israel-Hezbollah ceasefire has been in place since November 27, after more than a year of hostilities including two months of all-out war.

Despite the ceasefire, Israel has continued to carry out strikes on Lebanon, and both sides have repeatedly accused the other of violating the truce.

Under the deal, Lebanon's military was to deploy in the south alongside UN peacekeepers as the Israeli army withdrew over a 60-day period.

Israel has carried out hundreds of strikes in Syria since its civil war broke out in 2011, mainly on Iranian-linked targets.

Also Sunday, the Syrian Observatory for Human Rights war monitor reported Israeli strikes on a military airport in the southern Sweida province and an ammunition depot in the neighbouring Daraa province.

After a lightning rebel offensive toppled longtime Syrian strongman Bashar al-Assad in December, Israel carried out hundreds more air strikes on Syrian military assets in what it said was a bid to prevent them from falling into hostile hands.

Israeli troops also entered the UN-patrolled buffer zone separating Israeli and Syrian forces in the Golan Heights.