Defence Minister Richard Marles has ordered a snap assessment of the agency charged with delivering the $368 billion nuclear submarine program, amid complaints of a “toxic” workforce culture and staff churn.

One of Australia’s most experienced former mandarins, Dennis Richardson, will conduct a “stocktake” of the Australian Submarine Agency (ASA), including examining its internal structure and relationships with other bureaucracies and industry, senior government sources not authorised to speak publicly confirmed.