Opposition finance spokesman Stephen Jones acknowledged the program was established to provide financial relief for people experiencing income loss and hardship caused by the coronavirus pandemic.

But Mr Jones said the scheme had been marred by major theft and fraud and exposed taxpayers to the risk of fines and hefty tax bills.

"Government ministers and senior public servants have acknowledged many of these failings but have not provided any details as to the government's response," he wrote to the auditor-general.

"Despite these failings, the scheme is now being extended by the government for a further three months."

Australian Associated Press