The navy arrested four Costa Ricans and seized a shipment of cocaine in Colombia's territorial waters in the Caribbean, naval spokesmen on San Andres Island said Sunday.

The drug smugglers were using a lobster boat to transport the cocaine, whose weight is being determined.

The boat was spotted and boarded Saturday between Serrana Island and the Quitasueño banks, which are in the San Andres, Providencia and Santa Catalina archipelago.

A navy helicopter spotted the boat as it was "traveling at a high speed" toward Central America, the naval command said.

Marines from a frigate and a patrol boat boarded the boat, which was carrying 81 sacks filled with cocaine.

A navy plane had to fire warning shots to force the smugglers to halt.

The four Costa Ricans and the cocaine were transported to San Andres, where they were handed over to judicial authorities.

The navy has seized about 45 tons of cocaine and four tons of marijuana worth about $1.5 billion this year. EFE