"One explosion occurred before midnight (2100 GMT) in a hilly part of the Hula border zone and a second happened in the same district (on Sunday) morning," the official told AFP.
It "seems the two detonations were triggered by Israel which exploded two spying devices it had planted in the sector a long while ago," she said.
Israel "feared for one reason or another that they might be discovered and proceeded to destroy them by exploding them remotely," the official said.
Lebanese troops "located another device and exploded it on Sunday morning" after going to the area on Saturday night with UNIFIL peacekeepers, she added.
A security official in south Lebanon told AFP the devices were used for "surveillance of communications by the resistance," referring to the Shiite Hezbollah movement which fought a bloody 34-day war with Israeli in 2006 that devastated the south of the country.
Yasmina Bouziane, spokeswoman for the UN peacekeeping force, confirmed that UNIFIL troops had deployed in the area but said she had no "detailed information about what happened."
UNIFIL soldiers examine blast site (Photo: Reuters)
The military official also said Lebanese anti-aircraft guns fired at an "Israeli MK-type reconnaissance aircraft which violated Lebanese air space, overflying the southern region of Bint Jbeil".
"The army fired because the aircraft was within range," she added.
IDF: Hezbollah trying to divert attention
The Israeli army said the Lebanese allegations "do not warrant a serious response. We will continue to act to maintain calm on Israel's northern border."
"Hezbollah is once again trying to divert the attention of the international community from their continuous violations of UN resolution 1701. Today's incident proves Hezbollah's military presence in southern Lebanon, particularly in rural Shiite areas near the Israeli border," the army said in a statement.
Lebanon has repeatedly complained of violations of its air space by Israeli aircraft.
On October 12, a Lebanese man was wounded in a blast at a south Lebanon house occupied by a Hezbollah member.
Israel said the house was a Hezbollah arms depot but the militant group denied the claim and said a reaction between chemical products caused the explosion. Israel has protested to the UN Security Council.
The UN Security Council resolution, which brought an end to the 2006 conflict between Israel and Hezbollah, also required the Jewish state to stop overflights of Lebanon.