Doubts have surfaced over French shipbuilder Naval Group's commitment to incorporate at least 60 per cent of Australian content on the future submarines, including how it will be enforced and penalties for non-compliance.

Prime Minister Scott Morrison insisted the government's shipbuilding program was on track after The Australian Financial Review revealed the department may need to lease warships and enter public private partnerships for other acquisitions to save money because of a stretched budget for projects like the $80 billion submarine fleet.