An estimated 12.7 metric tonnes of marijuana were seized after the discovery of a cross-border tunnel. Authorities say it is one of the most significant secret drug smuggling passages ever found on the US-Mexico border.
The tunnel stretched about 366 metres and linked warehouses in San Diego, California and Tijuana, Mexico authorities said.
Mexican authorities recovered about 4.5 metric tonnes of marijuana south of the border while US authorities seized an estimated 8.2 to 9.1 metric tonnes inside a truck and at the warehouse in San Diego's Otay Mesa area, according to US Immigration and Customs Enforcement (ICE) agents in charge of investigations in San Diego.
The tunnel walls were lined with wood supports and power leads that trailed towards the Mexican entrance, suggesting lighting and ventilation systems had been in use below ground.
Several arrests were made, according to ICE officials, though no further details were released.
Cross-border tunnels have proliferated in recent years, but the latest find is one of the more significant, based on the amount of drugs seized.
Raids last November on two tunnels linking San Diego and Tijuana netted a combined 45.4 metric tonnes of marijuana on both sides of the border, two of the largest pot busts in US history.
Those secret passages were lined with rail tracks, lighting and ventilation.
As US authorities tighten their noose on land, tunnels have emerged as a major tack to smuggle marijuana.
More than 70 tunnels have been found on the border since October 2008, surpassing the number of discoveries in the previous six years.
Many are clustered around San Diego, California's Imperial Valley and Nogales, Arizona.
US authorities linked the November finds to Mexico's Sinaloa cartel, headed by that country's most-wanted drug lord, Joaquin "El Chapo" Guzman.
US authorities added that the sophistication of the latest tunnel suggested that a major Mexican drug cartel was involved, but no link has been established.
APTN