Chinese smugglers have allegedly dug a concrete tunnel into Hong Kong equipped with concrete walls and interior lighting to import mobile phones and other electrical goods.
The authorities believe that the smugglers could make huge profits by avoiding border fees and taxes as the semi-autonomous zone has different tariffs to the mainland, the BBC reports.
The tunnel was discovered last week in Changling village on the outskirts of Shenzhen, which started under a garage and stretched for 40 meters under a river and into reed-beds in Hong Kong, the report added.
The tunnel was thought to be incomplete, about 20 meters short of its intended destination, and was destroyed by the authorities.
The authorities traced the tunnel after a resident complained about drilling noises that she assumed were part of a renovation project.
Officials estimated the tunnel to have cost almost 500,000 dollars to build.