Three unarmed U.N. observers and two armed peacekeepers were hurt in scuffles with Hezbollah forces in southern Lebanon Thursday, the U.N. peacekeeping force commander said.

Tensions are high in the area along Israel's northern border, the scene of several clashes recently between Hezbollah and Israeli forces. There are fears the area could become a second front in the Middle East violence, in addition to the Israeli-Palestinian confrontation in the West Bank.

Israel, meanwhile, said Hezbollah fired still another volley of rockets at an outpost along the disputed border. There were no reports of injuries.

Prime Minister Ariel Sharon said the attacks, which have become an almost daily occurrance, were carried out with "Iranian approval and Iranian assistance" and could not have been carried out "without the full support and assistance of Syria."

Israel pulled its forces out of southern Lebanon in 2000 ending an 18-year occupation of the area.

The scuffle with Hezbollah forces broke out after an unarmed U.N. observer patrol reached the village of Mari, near the disputed Chebaa Farms area.

The observers — from Ireland, Norway and France — were confronted by Hezbollah gunmen who would not let them pass, a U.N. observer force officer said on condition of anonymity. An argument broke out, resulting in the gunmen beating up the observers.

A separate U.N. peacekeeping patrol — manned by armed Indian officers — was nearby at the time and intervened in the scuffle. This sparked a fist fight in which two Indians were hurt. Two U.N. vehicles were also damaged.

Secretary-General Kofi Annan strongly condemned the attack. An escalation of tension along the border "could have serious consequences for peace and security in the region," U.N. spokesman Fred Eckhard said.

The Irish U.N. observer suffered head injuries and was taken to the Israeli side of the border for treatment. The two others were treated at the scene and released. No word was available on the Indians.

A Hezbollah spokesman in Beirut refused to comment to The Associated Press. But the commander of the U.N. Interim Force in Lebanon, Gen. Lalit Tewari of India, said he received assurances from the guerillas that such incidents won't happen again. Lebanese authorities expressed concern over the fight, he said.

Col. Amol Astana, commander of the Indian peacekeeping contingent, said the patrol and the observers were confronted by eight to 10 armed Hezbollah members. Astana said his forces did not respond because their role is to act as peacekeepers. They reported the scuffle to Lebanese authorities.

Also Thursday, Staffan de Mistura, Annan's personal representative in Lebanon, met with Prime Minister Rafik Hariri to discuss the rising tension in country's south.