Israel's Mossad spy agency planted a small amount of explosives inside 5,000 Taiwan-made pagers ordered by Lebanese group Hezbollah months before Tuesday's detonations, a senior Lebanese security source and another source told Reuters.

Questions and speculation have swirled over where the devices came from and how they were supplied to Hezbollah .

Taiwan investigators searched four locations yesterday as part of a probe into the origin of pagers that exploded while being used by Hezbollah operatives