The ship, named the Gulfstream and sailing under an unidentified flag, had spilled 50,000 barrels of oil near Tobago's southern coast when it capsized in February and was found abandoned.

"There was an attempted unauthorized boarding of a support vessel by unidentified individuals" on Friday night, the energy ministry said.

"Officers attached to the Trinidad and Tobago Coast Guard were on-site and intervened. There was an exchange of gunfire, and one member of the response crew sustained a non-life-threatening injury."

The Gulfstream had recently been refloated and taken for salvaging to the Sea Lots area near Trinidad's Port of Spain, where the attempted boarding took place.

Police say Sea Lots is a hot spot for gang activity. The ministry said it is working with police and the army to protect the site.

The Gulfstream's ownership remains a mystery. The "Solo Creed," a barge that had been towing it at the time it capsized, had turned off its tracking beacon and then vanished, along with the crew.

The energy ministry said in May that official requests had been made to Tanzania, Nigeria, Panama, Aruba and Curacao to help track down those responsible.

Trinidad and Tobago, famous for its beaches and carnival, is an archipelago of 1.4 million inhabitants.

Its proximity to Venezuela has made it a favored stopping point for a variety of illicit trafficking.