(Reuters) - A U.S. judge jailed a Mexican truck driver for 15 years and 8 months on Monday for his role in a conspiracy to smuggle drugs through a sophisticated tunnel to California from Mexico.

U.S. District Judge Larry A. Burns sentenced Daniel Navarro-Chavez, 45, to prison at court in San Diego.

Navarro-Chavez was arrested in connection with the November 2010 discovery of a drug smuggling tunnel that ran about 600 yards under the border to a warehouse in south San Diego from a vacant commercial building in eastern Tijuana.

Police seized a total of 30 tons of marijuana in the operation, including 20 tons from the tunnel itself, and 10 tons on a semi-trailer truck that Navarro-Chavez helped escort in a red F-150 Ford pickup truck.

Federal prosecutors had sought a 30-year term for Navarro-Chavez. They argued that he was a leader of the smuggling conspiracy and knew about the tunnel and its operation.

Navarro-Chavez said he was simply hired to move marijuana from the warehouse to distribution points north of the border, and had no knowledge of the tunnel -- an assertion that his lawyer said was borne out by the sentencing.

We claim that he didn't know anything about the tunnels ... The judge saw the truth of it and was skeptical that Mr. Navarro was the ringleader, attorney Victor Sherman told Reuters.

A call seeking comment from the U.S. Attorney's office was not immediately returned.

The tunnel used by the organization to which Navarro-Chavez was linked was relatively sophisticated, and was equipped with a rail system, lighting and ventilation.

Authorities believe the tunnel, and another large passageway found three weeks later on the same block, were the work of Mexico's powerful Sinaloa Cartel, run by Mexico's most wanted man, Joaquin Shorty Guzman.

Tunneling under the U.S.-Mexico border has increased in recent years, as Mexican drug traffickers seek to beat beefed up enforcement at the U.S. ports of entry and the empty spaces in between.

In November alone, police found three tunnels running under the border from Mexico. Investigators found one measuring about 400 meters in the same area south of San Diego, and two shorter tunnels under the Arizona-Mexico border in Nogales.

Court California Mexico Arizona