The Netherlands will boost its military contribution to the NATO force fighting piracy in Somali waters after the country's Parliament approved funding.

The Dutch Parliament voted last week to spend $16.5 million to provide extra personnel, two Cougar helicopters and an unmanned aerial vehicle to join Operation Ocean Shield, in which NATO warships and aircraft have been patrolling the waters off the Horn of Africa.

Also part of the new deployment will be an additional submarine to join the mission in the second half of 2012, Radio Netherlands reported.

The Netherlands has committed two vessels to Operation Ocean Shield as part of the expansion of forces. They include the helicopter-carrying frigate Evertsen, which is on its way to the region, and the amphibious transport ship Rotterdam, which will carry the two Cougar helicopters as well as the drone, the national broadcaster said.

Meanwhile, the multipurpose frigate Van Amstel, which has been deployed as part of the EU's Operation Atalanta, will return to the Netherlands this month.

The mission of Operation Ocean Shield is to counter maritime piracy and build policing capacity with governments in the Horn of Africa region. It operates in conjunction with other naval forces including U.S.-led maritime forces, Operation Atalanta and national actors operating against the threat of piracy in the region.

The North Atlantic Council in March extended Operation Ocean Shield's mandate until the end of 2014.

NATO in May released new statistics on piracy in the region showing a marked decline in the number of hijacking attempts.

Officials said a five pirate hijackings were recorded over the first four months of 2012, which would put the region on a pace for 20 for the year. That's compared with 24 in 2011 and 45 each in 2010 and 2009.

But significantly, only 15 unsuccessful pirate attacks were seen between January and April -- a pace of 60 for the year -- while last year 129 such unsuccessful attacks by were recorded on shipping in the Somali Basin, the Gulf of Aden and the Arabian Sea.

As of May 11, pirates were holding eight ships with an estimated 235 hostages, NATO said.

A Dutch officer this month assumed command of Operation Ocean Shield. Commodore Ben Bekkering of the Dutch navy said the effort has been bearing fruit under the previous commander, Rear Adm. Sinan Azmi Tosun of the Turkish navy.

"On Admiral Tosun's 6-month watch, the success rate of pirates has seen a sharp decline," Bekkering said. "Pirates find it increasingly difficult to deploy from the coast and hunt at sea.

"But the many incidents over the last few months, including attacks and hijackings, make it absolutely clear that we can't let our guard down," he added. "I see it as my absolute task to ensure the trend continues and engage with all partners in the region to maximize our combined effect."

The Dutch Parliament at the same time, however, turned down an appeal from ship-owners to allow merchant ships to hire private protection forces.

Defense Minister Hans Hillen said he understood the ship-owners' position but said the government needed to retain control of armed forces at sea.

"All armed organizations have to fall under the state's responsibility to ensure accuracy and proportional measures," he told lawmakers.