Inside US-Mexico 'drugs tunnel'
13 July 2012 Last updated at 02:21 BST
Two sophisticated tunnels probably built to smuggle drugs into the United States have been found on the border with Mexico.
The tunnels were more than 200m (656ft) long and had lighting and ventilation.
A US agent said their design "wasn't something that an ordinary miner could have put together".
More than 150 tunnels have been found criss-crossing the US-Mexico border since 1990; most were crude passageways.