One of the country's top decision-makers has been seconded from the Department of Prime Minister and Cabinet to Bupa, the country's largest health insurer that is set to benefit the most from the $22 billion National Disability Insurance Scheme.

Rebecca Cross, the department's head of domestic policy was originally seconded under a program run in partnership between the Australian Public Service Commission and the Business Council of Australia, but in the first arrangement of its kind, has now extended her contract at the multi-billion-dollar insurer directly through an arrangement with Prime Minister and Cabinet.

The move has raised questions over a potential conflict of interest when she returns next year from the multinational insurer where she was acting as their head of government relations.

The Public Service Commission program has so far secured placements for 20 of the country's highest public servants in state and federal governments across companies such as Virgin, Deloitte and Qantas.