Three United Nations observers and an interpreter were wounded in shelling in Rmeish, southern Lebanon, the UN peacekeeping mission said.
Lebanon's state news agency said an Israeli drone strike was behind the blast, but the Israeli military did not claim responsibility.
The UN agency UNIFIL said the injured were being treated and the origin of the blast was being investigated.
This comes after rising tensions along the unofficial Israel-Lebanon border.
A shell exploded near the team on foot patrol along the UN-defined Blue Line that separates southern Lebanon from Israel, Unibil said in a statement.
It described the targeting of peacekeepers as “unacceptable”.
No details about the nationality of the visitors or their status were provided. The Lebanese translator is reported to be stable.
Lebanon's state-run National News Agency said Israeli “enemy drones” had raided the area in southern Lebanon where the bystanders were injured.
Israel's military denied this, saying in a statement: “Contrary to reports, the IDF [Israel Defense Forces] Unifil did not attack the vehicle in the Rmeish area this morning.”
In recent days, tensions have risen again along the unofficial border between Israel and Lebanon, with casualties on both sides.
Israel and the armed group Hezbollah trade almost daily strikes along the border, which began on October 7 with the start of the Israel-Gaza war following a Hamas attack on Israel.
Hezbollah is a Lebanese Shia Muslim militant group with close ties to Iran and an ally of Hamas.
On Friday, Israel's Defense Minister Yoav Gallant said the IDF would step up its attacks against the group in Lebanon, “from deterring to actively pursuing Hezbollah”.
He said we will reach them wherever they are hiding.
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