(Reuters) -Israel and Lebanon's powerful armed group Hezbollah exchanged artillery and rocket fire on Sunday following the deadliest attack in years by Palestinian gunmen on Israel.

There were no immediate reports of casualties in either Lebanon or Israel from Sunday's exchanges of fire.

On Saturday, a multi-pronged attack by Palestinian gunmen on Israeli towns left at least 250 Israelis dead, with more than 300 Palestinians killed in Israel's retaliatory bombardment.

Hezbollah, an armed party backed by Iran, said on Sunday it had launched guided rockets and artillery onto three posts in the Shebaa Farms "in solidarity" with the Palestinian people.

The Israeli military said on Sunday it fired artillery into an area of Lebanon where cross-border fire was launched. "IDF (Israel Defense Forces) artillery is currently striking the area in Lebanon from where a shooting was carried out," it said.

Israel's military said one its drones struck a Hezbollah post in the area of Har Dov, an area in Shebaa.

"At this point, there is no further threat in Har Dov or the northern arena," IDF spokesperson Daniel Hagari said in televised remarks, adding that the military remained on high alert.

The IDF later said that it fired a warning shot toward a number of "suspects" in the same area in Har Dov.

A Lebanese security source told Reuters that a tent set up by Hezbollah in the Shebaa Farms had been hit and that Hezbollah fighters had erected a new one.

FEARS OF 'CONFLAGRATION'

A second exchange of fire took place hours later, with two Lebanese security sources saying rockets fired from Lebanon again hit Israeli positions in the Shebaa Farms and that Israel responded with artillery fire on the village of Kfar Shouba.

There was no immediate comment from the Israeli military on a second exchange or from from the Lebanese army. A separate Lebanese security source, speaking on condition of anonymity, said the army had intensified its patrols in the south.

Israel has held the Shebaa Farms, a 15-square-mile (39-square-km) patch of land, since 1967. Both Syria and Lebanon claim the Shebaa Farms are Lebanese.

The United Nations peacekeeping mission in southern Lebanon, known as UNIFIL, said it had "detected several rockets fired from southeast Lebanon toward Israeli-occupied territory" as well as artillery fire from Israel into Lebanon in response.

"We are in contact with authorities on both sides of the Blue Line, at all levels, to contain the situation and avoid a more serious escalation," spokesperson Andrea Tenenti said.

The Blue Line is the demarcation line between Lebanon and Israel, marking the point to which Israeli forces withdrew when they left south Lebanon in 2000.

On Saturday, UNIFIL said it had enhanced its presence in southern Lebanon following developments in Israel and Gaza, including its operations to counter rocket launches.

The U.N.'s special coordinator for Lebanon Joanna Wronecka said on the platform X, formerly known as Twitter, that she was "deeply concerned" by the exchange of fire and urged parties to "shield Lebanon and its people from further conflagration".

Hezbollah, which effectively controls southern Lebanon, said on Saturday it was in "direct contact" with leaders of Palestinian "resistance" groups and that it saw Palestinian attacks on Israel as a "decisive response to Israel's continued occupation and a message to those seeking normalisation with Israel".