HMCS Winnipeg has made some important progress by deterring pirate attacks on ships off the coast of Somalia, says a Canadian naval commander.

"I think the coalition forces working together are certainly having a short-term impact here and making it much more difficult for the pirates to operate," Cmdr. Craig Baines told CTV's Canada AM Tuesday.

In fact, he said there hasn't been a successful attack in the region since May 7.

Baines is the captain of HMCS Winnipeg, which recently helped a ship evade pirates on May 22.

On Monday, the Canadian warship intercepted two boats carrying suspected pirates in the Gulf of Aden, seizing a large amount of firearms and rocket-propelled grenades.

A helicopter from HMCS Winnipeg spotted the two boats while on surveillance.

"In the last few days, the helicopter was able to see the suspected pirates and in a couple of cases was able to clearly see the ladders that they carry on board,"

"(It) was enough of an indicator for us to go and investigate and of course one thing led to another after that."

The frigate chased the boats and eventually boarded them. But after confiscating their equipment, the suspects had to be released, NATO officials said Monday.

NATO does not have an agreement with Kenya to hand suspected pirates over for trial.

The Winnipeg is one of five NATO warships patrolling off the Somali coast on an anti-piracy mission.

The European Union and countries including the United States, China, Russia and India are carrying out similar operations.

The Gulf of Aden is a crucial shipping lane crossed by 20,000 ships each year, and a haven for Somali pirates.

Under the circumstances, Baines said his crew has been exceptional.

"We do a tremendous amount of training in the navy, so to get to be out here doing operations and looking out for Canadian and international interest as part of the NATO coalition is very rewarding for the crew."