The new attack took place at approximately the same location as Thursday morning's attack in Naqoura.
UN Secretary-General António Guterres says that Israel's shelling of peacekeeping forces is "unacceptable" and must not be repeated.
The UN does not specify who is behind it, but according to media sources, it is Israel that has attacked again.
Two injured
In the first shelling, two people were also injured, in that case, Indonesian UN soldiers. The incident triggered strong reactions around the world, including condemnation from major powers that UN personnel were shelled in that way.
Israel's military says in a statement that it will "conduct a thorough investigation" into what happened. Israel says it has received information that "two peacekeeping UN soldiers were unintentionally injured in an Israeli operation against Hezbollah" in southern Lebanon.
The attack has sparked international reactions from several quarters. France, which is close to Israel, summoned the Israeli ambassador in Paris to lodge a diplomatic protest and demand an explanation.
The British government also expresses outrage over Israeli attacks on UN peacekeeping bases in Lebanon.
In turn, Lebanon's Prime Minister Najib Mikati demands that the UN adopt a resolution calling for an "immediate" ceasefire between Israel and Hezbollah.
Disarm militia groups
Mikati also emphasizes that the Lebanese government supports the 2006 UN resolution, number 1701, which stipulates that the Lebanese army and peacekeeping soldiers are the only armed forces that should operate in southern Lebanon.
The Lebanese government wants to strengthen the country's army along the border, according to Mikati. He claims that the Iran-backed Shia militia Hezbollah, which is Israel's main target in the war in Lebanon, shares the government's view on the matter.
According to resolution 1701, which aimed to put an end to the then ongoing war between Israel and Hezbollah, all militia groups in Lebanon were to be disarmed so that the Lebanese army was the only armed force – but that did not happen.
