Prosecutors say the ring was made up of two groups: one Spanish, the other Colombians hailing from Medellin, the EFE agency reported.
Colombian Carlos Eduardo Gomez put both groups into contact with one of the principal protected witnesses in the case, an infiltrator from the U.S. Drug Enforcement Administration.
The sting operation netted the cocaine Aug. 16, 2001, as it was being transferred from one ship to another off the coast of French Guyana.
On the first day of trial Monday, Spanish defendant Jose Ramon Prado told the judge the tens of thousands of dollars he was carrying in cash when arrested were nothing more than a loan to a friend.
Prado and his 14 co-defendants, for whom prosecutors are seeking prison terms of between 14 and 20 years, have been behind bars since their arrest in August 2001.
Also testifying Monday was Spaniard Juan Antonio Fernandez, for whom prosecutors are seeking 19 years in prison and an $868 million fine.