A Vancouver-area shipyard has been handed a $230-million contract to finalize the plans for the latest vessels in the federal government's national shipbuilding plan.

The agreement will see shipbuilding company Seaspan develop the production designs for two joint supply ships for the Royal Canadian Navy, with construction of the vessels expected to begin next year.

Judy Foote, minister of procurement and public services, announced the contract in North Vancouver on Tuesday, saying the deal will help create stable middle-class jobs.

Defence Minister Harjit Saajan says the ships will increase the "range, flexibility and duration" of Canada's navy by resupplying vessels at sea with fuel, food, ammunition and more.

The previous Conservative government originally launched the national shipbuilding strategy in 2010, budgeting $35 billion to rebuild the navy and coast guard fleets while also creating a sustainable shipbuilding industry on both the east and west coasts.

Foote declined comment Tuesday on the program's total cost, saying the number won't be known until all of the vessels have been completed sometime in 2021 and 2022, and that she doesn't want to give out preliminary numbers.

"From the perspective of the government, what we need to do when we give out numbers is make sure that they're real numbers. Because that's what we're contending with as a result of what happened previously," she said.

"The numbers that were put forward were unrealistic numbers that we had to contend with."

Seaspan is building three coast guard ships in Vancouver under the national plan. Foote said those vessels will be used to research fish stocks and monitor changes in the ecosystem, but will also be equipped to respond to emergencies like search-and-rescue operations.

The first of those three ships is expected to be delivered by early 2018, while the other two are scheduled for later in the year.