The source told The Daily Star the explosion occurred shortly before midnight Tuesday but the cause of the blast was unclear due to a heavy security clampdown imposed by Hezbollah.
The Lebanese newspaper, quoting local media reports, said the explosion occurred in a Hezbollah arms cache and Hezbollah prevented Lebanese military forces from reaching the site and cordoned off the area between the villages Siddiqin and Deir Ames.
There were no reports of injuries or any details concerning the extent of damage caused by the blast. Hezbollah officials refused to comment when contacted by the newspaper.
A spokesman for U.N. peacekeeping forces said they were checking the report, the paper said.
The explosion occurred in an area under U.N. control. Ynetnews.com said U.N. resolution 1701, which ended the Second Lebanon war in 2006, barred Hezbollah from storing arms in the area.