It ran underneath the main goods crossing between Israel and the blockaded Gaza Strip - known as Kerem Shalom - as well as gas and fuel pipelines, he said.
Conricus said Sunday Israel was defending its sovereignty with the destruction of the tunnel and was not seeking an escalation.
Israel holds Hamas responsible for any attacks coming from the coastal enclave.
Once a rare move, it will be the second time Kerem Shalom is punitively closed in under a month, as Israel seeks to force the ruling Hamas terrorist group to return quiet to the Gaza Strip.
Israeli military spokesman Jonathan Conricus said the tunnel belonged to Palestinian Islamist movement Hamas and was intended for attacks as opposed to smuggling.
Dozens of projectiles from Gaza have since targeted southern Israel, and 16 Palestinians were killed by Israeli forces, 14 in clashes and two in a retaliatory air strike on Gaza.
Israeli Prime Minister Benjamin Netanyahu said the tunnel was a "major terrorist infrastructure belonging to Hamas in the Gaza Strip".More news: Conte: There was no transfer talk when I spoke to Sanchez
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Violent riots raged in the Gaza Strip and across the West Bank as parts remain under military lock down following the shooting of a settler in the Nablus area last week, the Israel Defense Forces reported Friday.
On Saturday night the IDF announced it would be closing the Kerem Shalom crossing after an assessment of the current security situation, but did not provide further details.
According to official Palestinian media, that "infrastructure" was farmland in the southern Gaza Strip, prompting many to assume that it was, in fact, a tunnel beneath the field.
According to the IDF, rioters in four different locations along the Israel-Gaza border burnt tires and hurled rocks at Israeli security forces.
On Saturday, the Defense Ministry's chief liaison to the Palestinians warned residents of the Gaza Strip that the Hamas terror organization was using them in its quest for violence against Israel.
"The thwarting of the terrorist tunnel, the third in Israeli territory in recent weeks, is more proof of the IDF's advanced operational, intelligence and technological capabilities", read a statement by the IDF Spokesperson's Unit.