Ecuadorean authorities have discovered a 98 foot-long submarine being built near the country's Pacific Coast designed to carry drugs toward the United States.

For years, US and South American law enforcement officials have battled semi-submersible craft that travel just below the surface to avoid detection and take cocaine to Central America for trans-shipment to the States.

Authorities say the captured craft is the first designed to travel completely under water and was specially built for smuggling drugs.

One person was arrested when Ecuadorean police, assisted by US anti-drug intelligence, captured the diesel electric-powered submarine. It was fitted with a periscope and air conditioning and was being readied for its maiden voyage.

Ecuadorean military commander, Captain Carlos Albuja, said the sub could have ties to Colombia.

"We see that there are direct connections through a maritime route with Puerto Palma, which is in southern Colombia, that possible it could be an escape route of people that in some manner originates in that country," he said.

The Andean region is the world's biggest producer of cocaine and the United States represents the largest market.