Three Israeli soldiers have been killed and four others wounded in a guerrilla attack in south Lebanon.

Syrian-backed Hezbollah guerrillas have said they carried out the attack, which came only a day after the same group killed Colonel Akel Hashem, deputy head of the pro-Israel militia, the South Lebanon Army.

Reports say Monday's attack occurred near the heavily fortified former crusader castle of Beaufort - one of Israel's most important military positions in the region.

Two of the soldiers died immediately; the third a short time later. The dead and wounded were all airlifted by helicopter back to Israel.

The BBC Beirut correspondent, Christopher Hack, says the relatively large number of casualties suggests the soldiers were ambushed as they entered or left the castle.

Hezbollah spokesman Sheikh Atta told the French news agency AFP: "Our fighters opened fire with automatic weapons and launched anti-tank rockets at the Israeli unit, killing two of them and wounding many more."

Israel raids

Colonel Hashem died on Sunday when a remote-controlled bomb exploded near his car in the Israeli-occupied zone.

Israel responded by launching repeated attacks against Hezbollah bases in southern Lebanon.

Helicopter gunships launched up to ten attacks on Jarjaua, a village and wooded area just outside the Israeli-occupied zone which is thought to be used as an infiltration route by Hezbollah.

Earlier, Mr Barak said the colonel's death was a very serious incident, and promised that the killers would "receive their just punishment.

"We will make sure the situation does not deteriorate over the Israeli-Lebanese border and that the people who did that should be punished," he said.

Withdrawal pledge

Mr Barak has pledged to pull the army out of southern Lebanon by July, with or without an agreement.

The BBC's correspondent in Jerusalem, Hilary Andersson, says there are fears the SLA may respond with even more severity that the Israelis might wish.

She say the escalation of war in south Lebanon has the potential to derail the Syrian-Israeli peace process completely, particularly if the situation escalates further - as now seems likely - in the next few days.

SLA role

The mainly Christian SLA militia was formed during the Israeli occupation of southern Lebanon in 1978.

After invading Lebanon with more than 20,000 troops in retaliation against raids by Palestinian fighters, the Israeli Defence Force (IDF) pulled back, leaving the SLA to patrol much of the captured territory.

Israel says the zone, set up in 1985, is necessary to protect its northern territory from cross-border guerrilla attacks.

Hezbollah ('the Party of God') emerged in the 1980s, to fight "for the liberation of the occupied territories and the ejection of the aggressive Israeli forces".