Australian Prime Minister Malcolm Turnbull on Wednesday defended a decision to build a submarine fleet in partnership with France in Australia rather than opt for a faster build with initial work offshore.

Turnbull said Australia planned to sign a full contract with France's DCNS Group by the end of the year after announcing that the state-owned naval contractor beat bidders from Japan and Germany to win one of the world's most lucrative defense contracts, valued at 56 billion Australian dollars ($43 billion).

Turnbull acknowledged that doing the build entirely in Australia, rather than allowing DCNS to begin construction in France, would cost more, "but it's not the huge figure people have speculated about."