OTTAWA -- The multibillion-dollar effort to replace the navy's warship fleet has run into another delay.

The federal government says it is giving ship designers more time to come up with possible replacements for the navy's 12 frigates and three destroyers.

Officials say the move was necessary as some companies had questions that are still being answered.

But exactly when the new ship designs will now have to be submitted is still up in the air.

That could be cause for concern, as the government has been trying to close what is now a two-year gap between construction of the navy's new Arctic patrol ships and the much-larger warships.

Halifax-based Irving Shipbuilding, where the two fleets are being built, has previously warned of layoffs if the gap isn't closed.