The commander of UN peacekeepers inspected the scene after the discovery
Lebanese troops have deactivated four rockets ready to be fired at Israel, a day after a rocket attack caused Israel to respond with artillery fire.
The Lebanese military said three of the rockets were set with timers and left in a half-built house in Hula village, where Tuesday's attack was launched.
There were no casualties in the earlier exchange but it sharply raised tension on the volatile Israel-Lebanon border.
It was the fourth time rockets have been fired over the border this year.
The commander of the UN Interim Force in Lebanon (Unifil) Maj Gen Claudio Graziano has inspected the area where the rockets were found and where the nine Israeli artillery shells landed.
"The military has discovered this morning four rockets... in a house under construction belonging to the mayor of Hula," said a Lebanese military spokesman quoted by AFP.
The military said three Katyusha-type warheads were left on improvised wooden launchers in the garden of the house. One was left on a balcony.
The mayor was reportedly not in the village at the time of the incident and was not believed to have been involved.
Unifil officials said they had started an inquiry to ascertain who was responsible for the rocket fired on Tuesday, and they will be able to use Wednesday's discovery to gather more information.
There was no immediate claim of responsibility for Tuesday's rocket launch.
Israel fired an artillery barrage in response to it, saying that was sufficient retaliation under the circumstances.
However, Israeli officials said the situation was "grave" and that they held the Lebanese government responsible.
Cross-border tensions increased in October after an unexplained explosion near the southern Lebanese port city of Tyre and the detonation of two Israeli spy devices left over from the 2006 war.
Lebanese guerrillas from the Hezbollah movement were required to disarm in the border region under the UN ceasefire which brought hostilities to an end in 2006.
Hezbollah has denied involvement in any of the attacks and accuses Israel of breaking the ceasefire with continued overflights which violate Lebanese airspace.