Canadian naval helicopters fended off pirates attacking an American container vessel near the coast of Somalia on Friday.

The Canadian warship HMCS Winnipeg responded to the U.S. ship, Maersk Virginia, which was under attack in the Gulf of Aden. The ship is from the same fleet as the Maersk Alabama, whose captain was captured by pirates and held captive for four days in April.

CBS News correspondent Sheila MacVicar, who is aboard HMCS Winnipeg, reported that the Canadian ship first responded to a distress call by a Lebanese cargo vessel called the Maria K. The ship was reportedly under fire from rocket propelled grenades at the time of the call.

Within minutes, three naval helicopters from the Winnipeg took to the air in pursuit of Maria K, which was roughly 100 kilometres away. MacVicar said the pirates gave up their attack once they saw the helicopters and changed course, heading for the Maersk Virginia.

Joined by an Italian helicopter, the Canadian aircraft descended on the pirate vessel. With the helicopters hovering overhead, the pirates tossed their weapons overboard before Italian seamen boarded the vessel.

The Canadian forces have not provided any further details at this point, and Maersk Lines, Limited declined to comment on the event.

The Gulf of Aden is a crucial shipping route, but is infested by pirates. The Winnipeg is one of many ships that have been sent to the region to prevent further pirate attacks on cargo vessels.

The Maersk Alabama was attacked by pirates on April 8. The pirates eventually left the vessel with the captain after he offered himself as a hostage in exchange for allowing his crew to go free.

The hostage taking prompted a five-day standoff with the U.S. Navy.

U.S. Navy SEALS ended the confrontation by killing three of the captain's kidnappers and arresting one other. The captain escaped unharmed.

Prime Minister Stephen Harper praised the crew of HMCS Winnipeg in April after they chased and detained Somali pirates who tried to attack a Norwegian tanker in the Gulf of Aden.

The Winnipeg, patrolling with other NATO vessels off the Horn of Africa, responded to a mayday call issued by the Norwegian-flagged vessel Front Ardenne on April 18 after a band of pirates approached the vessel, officials reported.

The Winnipeg gave chase, along with U.S. and British ships, and warning shots were fired to get the pirates to stop, Canadian military officials said last month. After several hours of pursuit, Canadian sailors boarded the small skiff and detained the group.

They found a rocket-propelled grenade, said HMCS spokesperson Michael McWhinnie. But after further interrogation, the pirates were released.

Responding to questions why pirates were being released, Defence Minister Peter MacKay told CTV's Question Period earlier in May that it was because they are operating in a "flux zone" outside of territorial limits of coastal countries and therefore not subject to international law. But he said Canada is pursuing other legal avenues to prosecute the pirates.

He noted that several NATO allies such as the United States, France and Britain already have agreements with some African countries that allow for prosecutions on their soil.

Canada extended the anti-piracy mission of HMCS Winnipeg off the coast of Somalia after the federal government agreed to a NATO request for the frigate to continue operations as part of an allied effort to deter pirates.

MacKay said that Canada would be extending the ship's mission "into June," and possibly longer.

Pirates have attacked more than 80 boats this year, about four times than in 2003, according to the International Maritime Bureau.

With files The Associated Press