Canada wants to build navy support ships using a German design but isn't sure when it will get modern replacements for nearly its nearly obsolete vessels.

Canada's multibillion-dollar naval regeneration program has snowballed into a many-faceted point of controversy and inter-party recrimination. The support ships likely to be built using a German naval design are only a small part of a project that includes modern vessels to enable Canada project power in the arctic, where it's in competition with Russia and a whole range of European rivals.

Other parts of Canada's national shipbuilding strategy are still in early stages of development, with frequent opposition attacks on Prime Minister Stephen Harper's government for budget overruns, delays and alleged lack of clarity in the program.

Officials said the German design was chosen in a competition supervised by KPMG international audit consultancy. First Marine International, a recognized firm of shipbuilding experts, provided ship construction costings.

A proven off-the-shelf ship design from ThyssenKrupp Marine Systems Canada was selected as the best option for the Canadian navy and for Canadian taxpayers, officials say.

The design will be supplied to Vancouver Shipyards Co. Ltd. for review in preparation for production of two vessels meant as replacements for the 45-year-old Preserver and Protecteur.

That's part of a lengthy process, however, and Canada still needs to complete one of the next key stages -- obtaining licensing for the design.

The decision on design was driven by Canada's wish to build, operate and maintain the joint support ships in Canada and not be dependent on other countries.

Part of the plan is to develop shipbuilding expertise and capacity in the country as part of the country's shipbuilding procurement strategy.

Exactly how much the ships will cost remains unclear. Parliamentary budget officer Kevin Page said last month replacing the two existing supply ships could cost $4.13 billion -- way above $2.6 billion budgeted by the government, the Ottawa Citizen reported.

Kevin Page's report could spell more political trouble for Harper's Conservatives, "who've been hammered over delays and cost overruns in a series of military equipment projects," the newspaper said.

"The support ship program has traveled a long, convoluted path."

Proposals to replace aging support ships first surfaced in a defense white paper in 1994 but moves toward ordering new ships didn't begin until 2004.

Canadian shipyard proposals for building replacements were deemed too expensive by the Harper government in 2008, pushing it back again. Replacements for Preserver and Protecteur are not expected to be ready before 2018.

The chosen design is based on the German navy's Berlin Class Einsatzgruppenversorger, also known as EGV task force support ship, the German manufacturer said on its website.

The joint support ship is considered essential for the Canadian navy since the ships will be used to supply a maritime task group at sea with fuel, ammunition and food, Defense News said. The Protecteur and Preserver currently perform those roles.

The Berlin-class ships are 20,200 tons, almost 600 feet long and the Canadian versions will each carry two helicopters, Defense News said on its website. The German navy has three of the ships in service.