Lebanese security sources say five people were killed in an explosion at the home of a Hezbollah official in southern Lebanon.
Military personal were sent to the scene to investigate after suspicions were raised that munitions may have been stored in the building and exploded accidentally.
Both the official and his son are said to have died in the incident which happened within the area of UN peacekeeping operations.
Hezbollah has since denied that anyone was killed although they have said one person was wounded.
Israel claims the blast is evidence of the group stockpiling arms and is in violation of the truce which ended hostilities in 2006.
Both Israel and the US have accused Hezbollah of undermining peacekeeping efforts in the area.