An ammunition depot believed to belong to the Lebanese Shiite Movement Hezbollah, exploded early Wednesday in Southern Lebanon, Lebanese radio reported.
There were no immediate reports of casualties, DPA reported.
The Voice of Lebanon radio station said the blast occurred in the village of Siddiqine, east of the southern port city of Tyre.
Lebanese security forces tried to reach the area where the blast took place, but Hezbollah members had cordoned the site.
The village is located in an area controlled by the United Nations Interim Forces in Lebanon (UNIFIL), which monitors security at the Lebanese-Israeli borders in south Lebanon.
According to UN sources in southern Lebanon, the force has launched an investigation in the incident, but gave no further details.
Last year, several similar blasts occurred in villages, east of Tyre. At the time reports said the explosions went off at Hezbollah's weapon caches in the area, but the movement has always denied such claims.