Nov. 30, 2011  -- Federal agents in California have uncovered the "most sophisticated" drug tunnel in years, the latest discovery in what an official said had become a "major phenomenon" in the war on drugs.

A spokesperson for U.S. Immigration and Customs Enforcement declined to give details on the tunnel which ran from Tijuana to San Diego but said, "When we talk about a sophisticated tunnel, we're talking about tunnels that have some type of reinforcement in them and a lot of work has been put into them to help them smuggle the drugs in an easier way.

"In the past we have found tunnels that have railways and lighting and ventilation and all kinds of different scenarios and this is one of the most sophisticated that we have discovered perhaps ever, but definitely at least in the last five years," ICE spokesperson Lauren Mack said.

PHOTOS: Secret Drug Tunnels

The tunnel was discovered by San Diego's Tunnel Task Force in cooperation with Mexican authorities, Mack said. The task force, whose sole job is to uncover drug smuggling tunnels, is made up of agents from ICE, Customs and Border Protection and the Drug Enforcement Administration.

More than 70 tunnels have been discovered by federal authorities since October 2008, according to a report by The Associated Press, which first reported the new find.

Earlier this month, U.S. authorities nabbed 14 tons of marijuana from warehouses connected by a drug tunnel from Mexico to south San Diego. That tunnel was built with structural support and had the electric lighting and ventilation. Just a few days ago a pair of similar tunnels were uncovered in the Arizona border town of Nogales.

Mack said such tunnels had become a "major phenomenon ongoing increasingly in the last decade or so" for cartels in Mexico trying to get their product into the hands of U.S. customers.

Marijuana was also discovered in the new tunnel and Mack said federal agents were up late Tuesday night weighing it. The amount, along with other details about the tunnel, are expected to be revealed at a press conference in San Diego at 5 p.m. ET.

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