Longest smuggling tunnel on US-Mexico border found: Officials

US officials say they have discovered the longest smuggling tunnel ever found on the border with Mexico, a media report said.

Stretching for 4,309 ft (1,313m), the tunnel had a lift, rail track, drainage and air ventilation systems, and high voltage electrical cables, BBC reported.

It has an average depth of 70 feet (21m) below the surface, with the tunnel being 5.5 feet high and 2 feet wide, US Customs and Border Protection said.

The passageway connected an industrial site in the Mexican city of Tijuana to the San Diego area in California.

There were no arrests made or drugs found. Authorities did not say who they suspected of being behind the tunnel.

But Mexico's Sinaloa cartel, described by the US government as one of the largest drug-trafficking organisations in the world, operates in the area. Its founder and long-time leader, Joaquin "El Chapo" Guzman, is serving life in prison in the US.

The tunnel was discovered in August. Mexican officials identified its entrance and US investigators mapped it, before releasing the findings on Wednesday. It was not clear how long it took to build it.