A large explosion struck southern Lebanon near the border with Israel on Monday, the Lebanese official news agency reported.
South Lebanon is considered a stronghold of the country's militant Hezbollah movement. The group's guerrillas fought the Israeli army to a standstill in 2006.
Lebanon's National News Agency said it was not clear what had caused the early Monday blast near the border town of Tair Harfa.
Andrea Tenenti, a spokesman for the U.N. peacekeeping force in the area, UNIFIL, said its team was able to reach the site of the explosion and is investigating. Tenenti did not know what caused the blast and said there were no reports of casualties.
Lebanese security officials said Hezbollah had cordoned off the area of the explosion. The officials spoke on condition of anonymity because they were not authorized to speak to the media.
The situation along the Israel-Lebanon border has been tense in the past months due to the civil war in neighboring Syria and Israel's recent military operation in Gaza.
Last month, Lebanese security officials said two rockets were fired from Lebanon toward Israel, but fell short and landed on Lebanese territory.
Hezbollah is an ally of the embattled Syrian President Bashar Assad, while Lebanon's Sunni Muslims are backing the rebels fighting to topple his regime.