Hezbollah (search) and Israeli forces exchanged barrages of shells and rockets across the Lebanese border Friday and Israeli warplanes destroyed guerrilla positions in the heaviest clash in months between the two sides.

The flare-up in tension comes amid political turbulence in Lebanon (search). Hezbollah's ally Syria withdrew its troops from Lebanon last month, weakening Damascus's hold in the country — while Hezbollah has been seeking a greater political role.

The Israeli military accused Hezbollah of seeking to disturb the calm along the border and warned it will "not allow further provocations of any sort."

"Lebanon is obliged by the U.N. not to allow Hezbollah or other terror organizations to act. And as I said, if we have to respond we will respond," Maj. Gen. Benny Gantz (search), Israel's chief of the northern command, told reporters.

Hezbollah's Al-Manar television said its barrage was in retaliation for Israeli attacks on Lebanese territory, including a hit on civilian houses in the village of Kfar Chouba (search).

"The Islamic Resistance warns the Zionist enemy that any attack on civilians will be met with the appropriate response," the statement said.

In the clash, Hezbollah fighters fired a volley of shells and rockets at Israeli positions in the disputed border area of Chebaa Farms. Israeli forces fired artillery against the apparent source of the attack in the village of Kfar Chouba. Both sides claimed the other began firing first.

Witnesses counted at least 45 Israeli shells, and Israel said the barrage hit a Hezbollah position.

Warplanes and helicopter gunships then struck three more guerrilla posts, the Israeli military said. An Israeli tank also fired at a Hezbollah observation post near the village of Rmeish, witnesses said.

No Israeli casualties or damage were reported, an Israeli military spokesman said. There was no immediate word on casualties on the Lebanese side.

It was the heaviest clash between Israel and Hezbollah since January, when Hezbollah guerrillas blew up an Israeli bulldozer operating in Chebaa Farms and Israeli warplanes retaliated with strikes that wounded two Lebanese women.

Hezbollah is under international pressure to disarm, with a U.N. resolution demanding militias in Lebanon give up their weapons. The guerrilla group has refused, and Lebanese authorities have resisted pressuring Hezbollah, calling it a resistance movement, not a militia. The Lebanese army has not deployed in the south, allowing Hezbollah to keep security control there since Israeli troops ended their 18-year occupation in the area in 2000.

The guerrilla group's years-long confrontation with Israel has boosted its popularity in Lebanon, even beyond the country's Shiite community.

Some 2,000 protesters at a Hezbollah-orchestrated demonstration near the U.S. Embassy burst into cheers when news of the attack was announced. The protest has become a regular weekly occurrence to demand Washington stop interfering in Lebanese affairs.

Hezbollah sporadically attacks Israeli forces in Chebaa Farms (search) on the foothills of Mt. Hermon where the borders of Syria, Lebanon and Israel meet. A U.N.-drawn border that followed Israel's 2000 withdrawal put Chebaa under Israeli control, but Lebanon claims it. The United Nations says the region is part of Syria and occupied by Israel.

Friday's exchange came after days of sporadic shelling by both sides, which began when Israel mistakenly fired an artillery shell into Lebanon earlier this week while clearing explosives planted by the guerrillas near the border. The Israeli army said the shell caused no damage or casualties.