The 800m-long tunnel has a ventilation system, electricity, and a rail system Border police in the United States and Mexico have found a drug smugglers’ tunnel linking the Mexican city of Tijuana with California.
It is close to where police found a tunnel earlier this month, equipped with rails, ventilation and lights.
Police are still investigating, but local media are speculating the new tunnel, almost 800m (2,600ft) long, could be even be more sophisticated.
The authorities say it was used for smuggling marijuana into the US.
The tunnel leads from a house in Tijuana to a warehouse in Otay Mesa, California, the San Diego Tunnel Task Force said.
Officials said several suspects had been arrested as part of the operation and an amount of marijuana seized, although they did not say how much.
They said Mexican police and US agents were co-operating in the search of the tunnel, where they suspect to find more drugs.
Earlier this month, border police found more than 20 tonnes of marijuana during an operation centred on a smugglers’ tunnel running along a similar route to that found on Friday.
Police say drug traffickers are building the tunnels to bypass ever more stringent controls aimed at curtailing the cross-border trade in illegal drugs and guns.
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