SHEBAA, Lebanon: Hezbollah fired at least 20 rockets at Israeli-occupied Shebaa Farms in south Lebanon Friday in response to two Israeli airstrikes a day earlier.
The UN peacekeeping force, UNIFIL, said it detected rocket launches from Lebanon and return artillery fire by Israel.
"This is a very serious situation and we urge all parties to cease fire," it said in a brief statement.
UN Special Coordinator for Lebanon Joanna Wronecka said in a statement "maximum restraint is required to prevent further escalation."
"The Special Coordinator has called for all sides to refrain from violence and restore calm, in full respect of Resolution 1701, and to preserve security and stability," the statement added.
A Hezbollah statement said the group fired dozens of 122 mm rockets at "open ground" in retaliation for two Israeli airstrikes on open ground in south Lebanon early Thursday.
"The Islamic Resistance rocketed open ground near positions of Israeli occupation forces in the Shebaa Farms with tens of rockets," it said.
Israeli artillery positions responded to Friday's salvo by firing 155 mm rounds into the outskirts of Habbariyeh village near Shebaa as Israeli warplanes flew overhead. The Lebanese Army said at least 40 shells hit Lebanese territories, starting several fires.
Sirens warning of incoming rocket fire were sounded in northern Israel and the Israeli-occupied Golan Heights, the Israeli military said. There were no immediate reports of damage or casualties.
"Our understanding is that Hezbollah deliberately aimed at open areas in order not to escalate the situation," Israeli military spokesman Lieutenant Colonel Amnon Shefler told reporters.
The Israeli military said its Iron Dome system intercepted 10 of 19 rockets on Friday, with six falling in open areas and three landing inside south Lebanon.
There have been no reports of casualties or serious damage over the three days of aerial fire, which have jarred an extended period of relative calm since Israel and Hezbollah fought a one-month war in 2006.
Israeli Prime Minister Naftali Bennett's office said he was consulting with his defense and military chiefs over the violence. The military said it had struck "the rocket launch sites in Lebanon" Friday in response to Hezbollah's salvos.
The Israeli army said it 'does not want escalation' on Lebanon border but stands ready.
Some angry residents of the Lebanese Shwayya village in the area intercepted a truck with a rocket launcher as it drove through after the rockets were fired, a security source said. Lebanese Army soldiers detained four men and confiscated the truck, the Lebanese Army said.
A security source said in the evening the four Hezbollah fighters and truck were released hours laters
Hezbollah, in a second statement, confirmed that its men and truck had been intercepted by villagers after firing the rockets from a nearby location. It said it is always careful not to endanger the safety of residents.
Israeli Defence Minister Benny Gantz told his U.S. counterpart, Lloyd Austin, on Friday that Israel is "prepared for any scenario, and will continue to operate against Hezbollah or any of its proxies," according to a transcript from his office.
Gantz told the U.S. Defense Secretary that "additional action must be taken in order to thwart Iranian malign activities, including its nuclear program and attacks in the region and in particular its use of UAVs and missiles."
Thursday's airstrikes on south Lebanon were Israel's first in 15 years. Two rockets hit northern Israel Wednesday, drawing Israeli artillery fire.
Lebanon and Syria say Shebaa Farms are Lebanese while Israel says they are part of the Golan Heights, occupied by Israel in 1967.
The Lebanese government said Thursday it would lodge a complaint with the UN Security Council over the airstrikes.