The Israeli air force has launched a fresh raid against a Hizb Allah position in South Lebanon shortly after heavy exchanges of fire across the border.

"This attack targeted a position used by Hizb Allah to fire rockets and mortar shells at the north of Israel," an Israeli military spokesman said without giving further details of Tuesday's air strike.

On Monday, Hizb Allah rockets slammed into Israeli army outposts, and Israel's warplanes and shells hit the resistance group's targets in a sharp escalation of violence.

Aljazeera reported that four Hizb Allah activists had been killed and 11 Israeli soldiers wounded in the fighting which raged through the night and involved at least eight Israeli helicopter attacks on Hizb Allah targets.

Hizb Allah has acknowledged three of its fighters were killed and its Al-Manar TV station has said a fourth died of battle injuries.

Several casualties

The Israeli army said there were several casualties among soldiers in the border exchange, but would not give details.

Al-Manar television and other Lebanese stations said one Israeli soldier was killed and seven wounded in Hizb Allah fire and that two Israeli tanks were destroyed.

Lebanese Prime Minister Fuad Siniora spoke with the leadership of Hizb Allah and the American, French and Russian ambassadors in an attempt to defuse the tensions in southern Lebanon.

Abbas Nasir, Aljazeera's correspondent in Lebanon, said Siniora's conversations with Western ambassadors and the UN envoy appeared to be part of an attempt to contain the crisis and prevent further escalation.

Siniora may also be seeking to safeguard Lebanon against any damaging fallout at the UN and other international fora.

Witnesses in southern Lebanon said heavy exchanges lasted for two hours in the evening and continued intermittently into the night as Hizb Allah fighters fired truck-mounted rockets at Israeli army positions.

Israeli warplanes launched an air strike late on Monday night, Lebanese security officials reported.

Restraint urged

Hizb Allah fighters blamed Israel, but Israel said Hizb Allah attacked first and with the backing of supporters in Syria and Iran.

The US, which considers Hizb Allah a "terrorist" organisation, condemned the rocket attacks but also urged Israel to exercise restraint in its response.

Hizb Allah, which controls the Lebanese side of the border with Israel, is an ally of Syria in Lebanon. In recent weeks it has stepped up its criticism of the UN and its investigation into the killing of former Lebanese prime minister Rafiq al-Hariri.

Israel hinted on Monday that it was prepared for additional retaliation.

"Israel will do all possible to protect its residents in the north," Israeli Defence Minister Shaul Mofaz said.

He blamed Syria and Iran for the attacks, saying they were designed to ease international pressure on Damascus.

"Behind the fire in the north stand also Syrian and Iranian interests to ignite the northern border and turn the attention from Syria, which today is under heavy international pressure," Mofaz said.

In Washington, State Department spokesman Sean McCormack said the attack was a "deliberate provocation" by Hizb Allah and urged Lebanon's government to take charge.

Need to control

"We have made it very clear to the Lebanese government that they need to control the situation in southern Lebanon," McCormack said.

Hizb Allah has been disturbed about political change in Lebanon after the April withdrawal of the Syrian army in the wake of international and domestic outrage over al-Hariri's assassination.

The group, which led the guerrilla war against Israel's 1982-2000 occupation of part of southern Lebanon, is under international pressure to disarm under a 2004 UN Security Council resolution that demanded that all militias in Lebanon give up their weapons.

Hizb Allah has refused to lay down its arms under that resolution.