U.S. border cops find massive Mexico drug tunnel

LOS ANGELES (Reuters) - U.S. border police have found a sophisticated smuggler's tunnel the length of six football fields linking Southern California with Mexico and believed to have been used by drug traffickers, authorities said on Wednesday.

The U.S. Customs and Border Protection agency said the tunnel linked warehouses in Otay Mesa, California, and Tijuana, Mexico. It measured 1,800 feet and was equipped with a rail system, lighting and ventilation.

Agents also recovered more than 20 tons of marijuana during overnight searches of the tunnel, the border patrol said in a news release.

Mexican drug cartels have bored scores of tunnels under the U.S.-Mexico border in recent years to beat ramped-up security at ports of entry and the rugged spaces in between. Nearly all of them linked cities on either side of Mexico's border with California and Arizona.

In early 2006, agents discovered a tunnel measuring 2,400 feet running under the same stretch of border to Otay Mesa from Tijuana. It remains the longest such tunnel discovered to date.

Tijuana is the principal gateway for drugs entering California from Mexico. Last month authorities there seized more than 100 tons of marijuana valued at more than $340 million in Mexico's biggest pot haul to date.

(Writing and reporting by Tim Gaynor, editing by Steve Gorman and Cynthia Osterman)