Drug tunnel discovered

An agent from the San Diego Tunnel Task Force walks through part of the passageway of a tunnel found under the U.S.-Mexico border, in San Diego. -- PHOTO: REUTERS

SAN DIEGO - INVESTIGATORS suspect a major drug cartel was the driving force behind two long, sophisticated tunnels connecting Mexico with the US that were discovered this month along with more than 40 tons of marijuana.

Authorities said an underground passage located on Thursday was similar to one found earlier - both running around 610m from Mexico to San Diego and equipped with lighting, ventilation, and a rail system for drugs to be carried on a small cart.

The tunnels are believed to be the work of Mexico's Sinaloa cartel, headed by that country's most-wanted drug lord, Joaquin 'El Chapo' Guzman, said Mike Unzueta, head of investigations at US Immigration and Customs Enforcement in San Diego.

'We think ultimately they are controlled by the same overall cartel but that the tunnels were being managed and run independently by different cells operating within the same organisation,' Mr Unzueta said on Friday.

The tunnel found on Thursday is more than seven football fields in length and extends from the kitchen of a home in Tijuana, Mexico, to two warehouses in San Diego's Otay Mesa industrial district.

Three men were arrested in the United States, and the Mexican military raided a ranch in Mexico and made five arrests in connection with the tunnel, authorities said. -- AP