OTTAWA -- The federal government is scrambling to close a looming gap in the construction of two new fleets of naval vessels in Halifax, which Irving Shipbuilding has previously warned could result in layoffs if left unaddressed.

Officials say they are facing the likelihood of a break between when construction ends on the last of the navy's new Arctic patrol ships and when work begins on its new fleet of much larger warships.

The exact size of the gap still isn't known, and will depend on whether the government ends up with five or six Arctic ships and how much extra work must be done on whatever design is chosen for the navy's new warships.

Irving won't know until at least next year whether it will be able to build six Arctic patrol vessels within the government's $3.5-billion budget, or only five.

And the government doesn't know when a design for the new warships -- which will replace the navy's 12 frigates and three recently retired destroyers -- will finally be selected.

A dozen of the world's largest defence companies and shipbuilders were originally expected to submit their proposed designs for Canada's new warship fleet, known as the Canadian surface combatant, in April.

But the deadline has been pushed back several times, and while companies have until Thursday to provide technical information, government officials can't say when a design will actually be selected.

During Monday's technical briefing, Lisa Campbell, the head of military procurement at Public Services and Procurement Canada, would only say that the government plans to select a winner next year.

"It should be noted that the timing of the cutting of steel and delivery of the first ship is highly speculative at this point," Campbell said.

"We understand that not knowing the timing of production brings up more questions, such as the possibility of a potential production gap between the final Arctic offshore patrol ship and the first Canadian surface combatant."

Irving president Kevin McCoy, who appeared at the same briefing, said it was "way too early" to talk about potential layoffs at the company's Halifax facility.

But he previously warned in February that a gap could result in hundreds of workers getting paid to sit idle and or being let go, either of which would drive up the warship's already eye-popping $60-billion price tag.

"Shipyards are all about people, and particularly (for) a high-end combatant ship like the Canadian surface combatant, (it) is about having a skilled, trained, experienced workforce," McCoy said Monday.

"And our workforce is getting that experience now."

Irving has previously lobbied the Liberal government for additional work between the two naval fleets, including a new humanitarian ship or more Arctic patrol vessels, but those appear to have gone nowhere.

The two sides are instead now looking at other ways to fill the gap, which includes trying to learn from allies and searching for other countries that might be interested in buying some of the Arctic vessels.

"There are other nations out there who have a similar need to go into areas where there's ice. And so we've started a dialogue with some of those nations," McCoy said, without offering details.

"It may not pan out, but it may pan out," he added. "It's one of the things that we've engaged."