"They admitted gathering information on political party offices and monitoring the movements of party figures for this enemy."
"Communications devices and sophisticated cameras" were found in the possession of the accused, the statement said.
An army official declined further comment because of the continuing investigation.
The Bekaa Valley in eastern Lebanon is considered to be a stronghold of the Shia group Hezbollah.
Hezbollah and Israel fought a 34-day war in 2006 that left much of Lebanon's infrastructure destroyed and claimed the lives of more than 1,200 Lebanese, mainly civilians, and more than 160 Israelis, mostly soldiers.
Israel, which also invaded Lebanon in 1982 and kept troops in a "security zone" in the south until May 2000, has been previously linked by security sources to assassinations of public figures.
In June 2006, the Lebanese army uncovered what it said was an Israel-linked network it accused of being behind the killing the previous month of Mahmoud Majzoub, a senior Islamic Jihad leader, and his brother Nidal in a car bombing in the southern port city of Sidon.