An explosion on Wednesday wounded Israeli soldiers who had crossed the border into Lebanon in a rare incident on the heavily guarded and volatile frontier, the Lebanese army said.

The army said in a statement that the Israeli force reached as far as 400 metres inside Lebanon. The statement said the army is investigating the nature of the pre-dawn blast, which occurred in the area of Labbouneh near the coastal town of Naqoura.

The Israeli military said earlier that an explosion near Israel's northern border wounded four soldiers.

The Lebanese army called the incident "a new violation of Lebanese sovereignty."

Lebanon's state-run National News Agency said the soldiers were wounded by a land mine about 150 metres inside Lebanon. (Google)

Israel fought a month-long conflict with the Iranian-backed Lebanese group Hezbollah in 2006 and sometimes there are cross-border attacks.

The 2006 conflict, that killed about 1,200 Lebanese and 160 Israelis, was triggered when Hezbollah guerrillas crossed into Israel and captured two Israeli soldiers.

Israeli Prime Minister Benjamin Netanyahu wished the soldiers a speedy recovery while on a tour of a military base in the south of the country. "We will continue to act responsibly in order to defend Israel's borders," Netanyahu said.

The military said Wednesday that the soldiers were hurt during "overnight activity adjacent to the northern border." It did not say if they were injured in training or in combat, and refused to elaborate further. Israel borders both Lebanon and Syria on its north.

Lebanon's state-run National News Agency said the soldiers were wounded by a land mine about 150 metres inside Lebanon.