Hezbollah (search) guerrillas attacked an Israeli base in a disputed part of the south Lebanon (search) border on Wednesday, and Israel responded with an airstrike. Israel said it suffered casualties in the exchange.

The guerrillas attacked three Israeli positions in Chebaa Farms (search), an area where the borders of Lebanon, Syria and Israel meet, Hezbollah's Al Manar TV channel and Lebanese security officials said. The officials said the attack was with mortar shells and rocket-propelled grenades.

Israeli Defense Force officials said Hezbollah carried out a coordinated attack, firing mortar shells and small arms at one of their bases in Chebaa Farms. The base was hit and there are Israeli casualties, the officials said, but they declined to be specific.

Israeli Army Radio reported there were three points of contact in the ongoing clashes near the base.

In response, Israel shelled suspected guerrilla hideouts near the town of Kfar Chouba in the vicinity of Chebaa Farms, Al Manar reported.

Israeli officials, who spoke on customary condition of anonymity, said Israeli warplanes struck Hezbollah positions in south Lebanon. Lebanese officials confirmed the Israeli airstrike.

A group of Hezbollah fighters crossed the border during the attack and the Israeli Defense Force was searching for them, the officials said.

Al Manar said a number of Israeli soldiers were wounded in a Hezbollah ambush "after they trespassed the blue line" — the U.N. demarcated border.

Chebaa Farms has become the focus of Hezbollah attacks on Israeli forces since the Jewish state withdrew its troops from southern Lebanon in 2000. Hezbollah attacks the enclave periodically, the last time being on May 21.

Lebanon and Syria say Chebaa Farms is Lebanese territory, but U.N. cartographers who surveyed the border after the Israeli withdrawal said it belongs to that part of Syria which Israel has occupied since the 1967 Arab-Israeli war.

Hezbollah, which led a guerrilla war against Israel's 18-year occupation of part of southern Lebanon, is under international pressure to disarm. A U.N. Security Council resolution passed in September demanded that all militia in Lebanon give up their weapons.

The guerrilla group has refused, and has so far been supported by the Lebanese government, which claims Hezbollah is not a militia but a movement resisting Israeli occupation.