A maritime regulator in New Zealand said it pulled two hazardous notifications related to the 2011 wreck of a cargo vessel, which caused oil to spill offshore.

Up to 2,000 barrels of oil leaked from cargo ship Rena after it struck a reef in the Bay of Plenty in October 2011. Keith Manch, the director of Maritime New Zealand, said two notifications regarding hazards associated with the wreck were withdrawn.

"While some oil remains trapped in the wreckage of the vessel, most of the harmful substances contained within the ship have been discharged into the sea and have either been removed or have been, and will continue to be, monitored under the plan provided for under the resource consent," he said in a statement.

Thousands of barrels of oil reached New Zealand shores after the cargo vessel struck the reef. Bad weather hampered response efforts in 2011 and nearly 400 emergency responders were on hand at any given time for cleanup operations tied to the Rena wreck.

Manch said crews had pulled more than 20,000 tons of debris from the seabed since response operations began in late 2011.

"The information and evidence available to me indicates that all reasonable efforts have been made to remove entanglement hazards and wreckage, where possible," he said "I have concluded that the wreck and remaining debris on the sea floor no longer constitute a hazard to navigation."

Daina Shipping Co., the ship's owner, entered a guilty plea to charges related to the discharge of harmful substances and fined $300,000. The company reached a $22.8 million settlement with the New Zealand government.

Two of Rena's crewmembers were given short prison terms after pleading guilty to a total of 11 charges related to the grounding.