Police in Ecuador seized a 100-foot submarine being built by suspected drug traffickers capable of carrying a crew of six and 10 tons of cocaine on underwater voyages lasting up to 10 days — a “game changer” for U.S. anti-drug and border security efforts, officials said Monday.

A raid Friday by 120 police officers and soldiers netted the fiberglass sub as it was nearing completion in a clandestine “industrial complex” hidden in mangrove swamps near San Lorenzo, a town just south of the Colombian border.

The craft was outfitted with a conning tower, a periscope, air conditioning and “scrubbers” to purify the air, and bunks for a maximum crew of six. But what set the craft apart from semi-submersible craft that drug traffickers have used for years was a complex ballast system that would have enabled it to dive as deep as 65 feet before surfacing.

Previously, drug traffickers were known to use ships that resembled submarines but that actually cruised just below the ocean surface to avoid visual detection.

Since 2006, when the first semi-submersible craft was detected, 47 have been captured at sea and on land, including 17 last year. But so far this year, only three such craft have been captured. The number of voyages has probably dropped, officials said, because of the success in detecting the vessels with a variety of methods, including aircraft that can identify their wakes in the water.

The sub that Ecuadorean police seized on their Pacific coast is much more technologically advanced and will require the U.S. and its allies in the drug war to deploy “every resource” in anti-submarine warfare technology, said Jay Bergman, the U.S. Drug Enforcement Administration’s Andean director.

Those countermeasures could include added oceangoing and airborne surveillance vessels and aircraft, he said.

“This is a game changer for us and will prompt an array of countermeasures,” Bergman said in a telephone interview. “This has the national security community concerned as much as the drug interdiction community.”

U.S. military officials have long expressed the fear that narco-submarines could, in addition to carrying illicit drugs, be used to smuggle terrorists to U.S. shores or nearby.

One Ecuadorean national was captured by police and soldiers, some of whom swooped in by helicopter. The suspect is cooperating with authorities. The shipyard included a camp that was big enough to accommodate 50 workers, officials said.

Ecuadorean authorities said in a statement Monday they believe the ship had a maximum speed of 8 knots and could have made underwater voyages lasting up to 10 days, long enough to reach the Pacific coast of Mexico. The cost of the ship, which had twin diesel engines, was estimated at $4 million.

Neither the designer of the sub nor the provenance of the equipment was known. The periscope appeared to be military-issue, but Bergman declined to speculate on which country it came from.

Counternarcotics officials have long expected to find a submarine such as the one captured in Ecuador, Bergman said, seeing it as the logical step in the gradual evolution of traffickers’ methods, which include human “mules,” private aircraft, speedboats and concealment in bulk cargo.

Officials at Bogota’s El Dorado airport last week seized more than 24 pounds of cocaine hidden inside a facsimile of the World Cup championship soccer trophy.

The seizure of the submarine also reinforced concerns that Ecuador is becoming increasingly important for drug traffickers squeezed by interdiction efforts in Colombia, where the U.S. government spends $550 million a year on counternarcotics and anti-terrorism operations.

The United Nations Office on Drugs and Crime said in its annual report last month that the number of acres Colombian farmers dedicate to illegal crops of coca, cocaine’s base material, declined last year to 170,000 from 250,000 in 2008. Meanwhile, Ecuadorean anti-drug police last year seized a record 68 tons of cocaine, more than double the 2008 total.

“As far as the engineering that went into this, you have to marvel at the lengths they are going to avoid capture,” Bergman said of the captured submarine. “The real technological trick is not building a sub that will dive down, but one that will come back up, and they seem to have mastered the challenge.”

Kraul is a special correspondent.