Beirut, Aug 4 (DPA) Hezbollah Secretary-General Sayyed Hassan Nasrallah described Tuesday the lethal border clash between the Lebanese army and the Israeli troops earlier as "heroic", and warned his militia would retaliate if there were further incidents.

At least two Lebanese soldiers, and an Israeli soldier, and a Lebanese journalist were killed in the exchange of fire. It was the most serious clash since Israel and Hezbollah guerillas fought a bitter war in 2006.

"The army fought heroic confrontation with the Israeli enemy in southern Lebanon," Nasrallah said in a speech marking the fourth anniversary of the 2006 war with Israel.

The clash, coming amid heightened tension between the two neighbours, was unusual in that involved the Lebanese army, rather than Hezbollah militias.

Nasrallah said that his movement's guerrillas were on standby to back the army.

"This time we stood and watched ... but next we will not," he warned.

"Israel's aggression on Lebanon has never stopped. We will not stand idle ... we will cut any hand that attack our army," Nasrallah said.

A Lebanese security official said at least two Lebanese soldiers were killed and several others wounded, some of them seriously.

A Lebanese journalist, working for the al-Akhbar newspaper, which is close to the Hezbollah organization, was also killed.

An Israeli lieutenant-colonel in the reserves, a battalion commander, was also killed, the Israeli military confirmed late Tuesday.